When I first saw this news on MacRumors this morning, my immediate thought was "Duh! China has 4.4 times the population of the U.S." But there's more to the story of China passing the U.S. in iOS and Android activations, since the per-capita income is almost twelve times greater for Americans than it is for the average Chinese citizen.
The information from mobile analytics firm Flurry is pretty astounding, showing a steady rise in the percent of total acti