A new data set on the HIV epidemics in each country since 1979 is now available in Gapminder World. The dataset is an expansion of the excellent UNAIDS data, and illustrates several interesting points.
Here is a moving graph with the percent adults infected with HIV in each country plotted against the GDP per capita. The size of the bubbles shows the number of people infected with HIV in each country (not the total population, as is usual in the Gapminder graphs). Click Play to see the epidemic from 1979 to 2007, and to see new surprising trends.