Instead of studying history for one year at the university, you can watch this video for less than five minutes.
Income per person (GDP per capita) is adjusted for inflation and for differences in costs of living (purchasing power) across countries. You can play with the data yourself in Gapminder World.
Will saving poor children lead to overpopulation?
Hans Rosling explains a very common misunderstanding about the world: That saving the poor children leads to overpopulation.
Not only is it not right, it’s the other way around!
Hans Rosling: Norges suksess på 5 minutter