In my “100 Charts Project” I am presenting the 100 most important charts from and will explain briefly what the charts shows and why it is important.

[7/100] We are making progress against the world’s biggest environmental problem



What this chart shows:

Indoor air pollution is by far the biggest environmental problem of the world. Every year, 4.3 million people die due to the exposure to household air pollution caused by indoor open fire. To bring this in perspective: This is 45-times the number of the global annual deaths from natural catastrophes (±95,000 in the 2010s). And much more than twice the number of people dying because of AIDS (1.5 million in 2013). It is probably the most unreported of the world’s big problems.

The burning of solid fuels fills the houses and huts in poorer countries with thick smoke that kills the world’s poor by causing pneumonia, stroke, heart disease, chronic obstructive pulmonary disease, and lung cancer. It is predominantly women and young children who are killed by indoor air pollution.

The solid fuels responsible for this include wood, crop residues, dung, charcoal, and coal.

The solution for this problem is straightforward: shift from solid fuels to modern energy sources. And the chart shows that we are making rapid progress in this direction. In 1980 almost two thirds of the world’s population used solid fuels for their cooking. 30 years later this is down to 41%. The chart also shows that it is a problem associated with poverty: In richer Europe and North America the share is much lower than in the rest of the world; and in the high income countries of the world the use of solid fuels is entirely a thing of the past.

The use of solid fuels is going down in all of the world’s regions. But the success rapidly developing South East Asia is particularly impressive: Here the share fell from 95% to 61%.


This is part of my 100 chart project.

Data Sources:

These data are taken from Bonjour et al. (2013) – Solid Fuel Use for Household Cooking: Country and Regional Estimates for 1980–2010. Environ Health Perspect; DOI:10.1289/ehp.1205987. Online here. The data  (by country) is available in the supplemental material document which is online here.

The authors are Sophie Bonjour, Heather Adair-Rohani, Jennyfer Wolf, Nigel G. Bruce, Sumi Mehta, Annette Prüss-Ustün, Maureen Lahiff, Eva A. Rehfuess, Vinod Mishra, and Kirk R. Smith.

Countries are grouped by WHO region and income category (WHO 2012e; see Supplemental Material, Table S2).

Link to

You find this chart and much more information about this topic in the data entry on indoor air pollution.

[6/100] When more infants survive – fertility goes down


What this chart shows:

On the y-axis we measure the number of annual live births per 1,000 people.

On the x-axis we measure how many infants, who were born alive, survive their 1st year of life – this is the infant survival rate.

The chart shows how these two aspects changed over the course of the 20th century: At the beginning of the century all 4 countries can be found in the upper left corner – they are characterized by high fertility and an infant survival rate below 85%. If we follow the 4 lines we are taken to the bottom right corner and see that women have fewer children when the mortality rate of babies goes down.

The causal link between infant survival and fertility is established in both directions: Firstly, increasing infant survival reduces the parents’ demand for children. And secondly, a decreasing fertility allows the parents to devote more attention and resources to their children.

This link between fertility and child mortality is an immensely important insight and tells us what drives the acceleration and slowdown of population growth: In the initial stage of the transition, when fertility rates are still high but health is already improving, the population starts to grow. But then, a bit later, we see that this transition works to decrease population growth since improving health of the children leads to lower fertility. It is an important part of the mechanism behind the demographic transition.

A very cynical view – that I heard more than one time as a reply on my twitter – is that a decrease in child mortality is bad for the world since it would contribute to the overpopulation of the planet. The chart above shows that this opinion is not just contemptuous of human life but plainly wrong: When more infants survive fertility goes down and the temporary population growth comes to an end. If we want to ensure that the world’s population increase comes to an end soon we must work to increase child survival.

Data Sources:

The data is taken from the International Historical Statistics (IHS), edited by Palgrave Macmillan Ltd. (April 2013). The online version is available here. As a printed version it is published by Palgrave. The child survival rate is calculated using the IHS Data ‘Deaths Of Infants Under One Year Old Per 1,000 Live Births’.

Link to

You find this chart and much more information about this topic in the data entry on fertility.

[5/100] The World is Much Better Educated than in the Past



What this chart shows:

Looking at the graph on the top we see that in 1870 more than 3 quarters of the world’s people never had the chance to go to school. Looking at the graph at the bottom we see that this meant was that a similar small share – 19% – of the world were able to read.

The low average figure of education attendance hides huge inequality between world region. While in Europe and the Western Offshoots in North America and Oceania more than half of the population had attended school in 1870, the share was much lower in other parts of the world: In Africa and South-East Asia more than 90% of the population never went to school.

Today the global average has risen to 82% and the inequality between world regions – while still existing – is much lower.

Two centuries ago only a small elite of the world had the ability to read – the best estimate is that 12% if the world’s people were literate. Over the course of the 19th century this number more than doubled. And over the course of the 20th century the world achieved rapid progress in education. More than 4 out of 5 people are now able to read – and from my map at OurWorldInData we can see that it is mostly older people that are illiterate. The young generation is much better educated than ever before.

The much better education of the world population is what makes me most optimistic about the future.

Data Sources:

The data for world average literacy and formal education by world region are from van Zanden, J.L., et al. (eds.) (2014), How Was Life?: Global Well-being since 1820, OECD Publishing. Online here.

The attendance of at least some formal education refers to the population aged 15 and older.

Link to

The interactive version of the chart at the top is available in the data entry covering the global rise of education.

The chart at the bottom – and much more on literacy – can be found in the data entry on literacy.

[4/100] The rapid decline of maternal mortality


What this chart shows:

I cannot imagine not imagine a more tragic time to lose your life than in the very moment you are giving life to your child.

The chart shows how much rarer maternal mortality has become. Let’s look back a hundred years: Out of 100,000 child births about 500 to 1,000 ended with the death of the mother. This means every 100th to 200th birth lead to the mother’s death. Since women gave birth much more often than today the death of the mother was a common tragedy.

The decline of maternal mortality to around 10 per 100,000 is due to the modern scientific understanding of the cause of maternal mortality and the adoption of very simple practices. The common reason for the mother to die was puerperal fever (or childbed fever) which was caused by unhygienic medical staff and medical equipment by which the mother’s genital tract is infected during childbirth. It was the physician Ignaz Semmelweis who first noticed the link between hygiene and the survival of mothers in the middle of the 19th century. He urged his colleagues to wash their hands with chlorinated lime solutions but was ignored. The germ theory of disease was not yet known and therefore  he could not explain why there should be a link between hygiene and the survival of women during childbirth. The rejection by the medical community of the time turned Semmelweis bitter and every conversation he had revolved around childbed fever. He was eventually committed to an mental asylum where he died a miserable death. He was never to see how right he was and never knew how many mother’s lives he saved!

After Semmelweis’ death, when Louis Pasteur developed the germ theory of diseases, the recommendations of Semmelweis were finally adopted and maternal mortality started to decrease. A procedure as simple as the doctor washing his hands meant that puerperal fever – a killer of thousands of mothers – declined sharply. We see the decline in Finland over the course of the 2nd half of the 19th century. In the 20th century the availability of antibiotics made it possible to treat cases of puerperal fever and the death of a mother is today fortunately very rare.

As it is often the case we see that it is much harder for a pioneer to make advancements than for a country that catches up later. The decline of maternal mortality in Finland began in the middle of the 19th century and didn’t reach today’s low level more than a century later. Malaysia in contrast achieved this progress in only a few decades.

Data Sources:

The visualized data is taken from Claudia Hanson (2010) – Gapminder Documentation 010 – Documentation for Data on Maternal Mortality Historical information compiled for 14 countries (up to 200 years). The accompanying document and the data set from which I have taken this data is online here. It shows the maternal mortality ratio (per 100,000 live births). The indicator is defined as follows by the source: ‘The number of maternal deaths divided by the number of live births in a given year, multiplied by 100,000. Maternal death is defined as the death of a women while pregnant or within the 42 days after termination of that pregnancy, regardless of the length and site of the pregnancy, from a cause related to or aggravated by the pregnancy.’ If data is given for time brackets of more than a year then I have plotted the observation at the midpoint of the bracket.

Link to

The interactive version of this chart – showing maternal mortality also for other countries – is available in the data entry on maternal mortality.

Much more common was the death of the child – every 3rd child died before the 5th birthday (see the data entry on child mortality).

[3/100] Gains for all – Life Expectany by Age




What this chart shows:


Every time I talk about the increase of life expectancy there is at least one person who claims that this is not very meaningful as this statistic “is skewed” by the decrease in child mortality. Yes, child mortality matters a lot – but there is more to the increase in life expectancy than this. This chart shows it!

Before the onset of modernity – with the advancements in science and the increase of living standards – life was short. As we have seen in the1st chart in this series, in 1800 there was no country in the world where the life expectancy was higher than 40 years.

The gains in life expectancy since then were mostly due to changing mortality patterns at a young age: It was common that every 3rd or even 2nd child died, and it has dropped dramatically since then. See the data entry on child mortality on OurWorldInData.

But this chart here shows that the increase of life expectancy was by far not entirely due to the decrease in child mortality: Child mortality is defined as the number of children dying before their 5th birthday. To see how life expectancy has improved without taking child mortality into account we therefore have to look at the prospects of a child who just survived their 5th birthday: In 1845 a 5-year old had a expectancy to live 55 years. Today a 5-year old can expect to live 82 years. An increase of 27 years!

And also at higher ages mortality patterns have changed. A 50-year old could expect do live twenty more years. Today the life expectancy of a 50-year old is 83!

And another important change can be studied in this chart: Health inequality decreased hugely! Look by how much life expectancy differed by age in 1845 – from 40 years for newborns to 79 for 70-year olds. Today this span is much smaller – from 81 to 86. This is because the chance of dying at a younger age has been steadily decreasing, which means that the equality of life spans has increased.

Data Sources:

The data for life expectancy by age is taken from the Human Mortality Database. University of California, Berkeley (USA), and Max Planck Institute for Demographic Research (Germany). Available at (data downloaded on 11 February 2014 – being granted permission to use this data for the visualisation on 13 February 2014).

The data on life expectancy at birth before 1845 is taken the data from Kertzer and Laslett (eds) (1995) – Aging in the Past: Demography, Society, and Old Age. Berkeley: University of California Press. Online here. Their sources are the ‘British official statistics’ and Wrigley and Schofield [1981] 1989.

(The Human Mortality Database data refers to remaining life expectancy for people in a 5 year age bracket (10-14, 15-19, …). To calculate total life expectancy I have added the lower bound of each range to the remaining life expectancy for the given age group – the values here should therefore be understood as the lower bound for total life expectancy.)

Link to

The interactive version of this chart – showing the life expectancy by 5-year interval up to the age of 110 – is available in the data entry on life expectancy.