Extreme poverty has fallen.

This is probably the most important chart on this list. The extraordinary rate of economic growth in India and China — as well as slower but still significant growth in other developing countries — has led to a huge decline in the share of the world population living on less than $1.25 a day, from 52 percent in 1981 to 43 percent in 1990 to 21 percent in 2010. That's a low bar for what counts as poverty, and some development experts are arguing we should be using a global poverty line of $10-15 a day instead, but that very debate is a sign of the tremendous progress made in recent decades.