Tracking the spread of AIDS
Adam Cole and Nelson Hsu for NPR plotted the percentage of people, ages 15 to 49, living with HIV from 1990 to 2009.
By 1990, the world had a pandemic on its hands. In 1997, the peak of the epidemic, more than 3 million people became newly infected with HIV.
Then science struck back. Drugs approved for HIV treatment in the mid-1990s proved profoundly effective, transforming AIDS from a death sentence to a chronic illness. Those treatments, combined with an international commitment to manage the disease by providing access to free drug therapy, led to a steep drop in new HIV infections.
The countries in middle, eastern, and southern Africa stand out in the chart, like Swaziland with a whopping 25.9%, but most areas cluster well below five percent. Although the drop-down filters help some with country selection, the data probably would've benefitted from a chart that had a self-updating vertical axis.