For developers, the more significant figure might be a second one: the App Store has generated more than $7 billion in payments to developers. Remember, too, that Apple gets a portion of the revenue generated by App Store sales, either directly or in-app.
Apple's take is 30 percent, which means -- extrapolating from the $7 billion, which would have been 70 percent of the overall take, Apple received around $3 billion from the App Store, itself.
That’s still a fraction of Apple’s revenue, $36 billion in the calendar year fourth quarter last year (which was Apple's fiscal Q1 2013), but Apple sees the App Store and its revenue as just part of the ecosystem it has which includes devices, software, iTunes, and more.
For developers, the rate of increased pay seems to be increasing. In March of 2012, Apple said it had hit 25 billion downloads, but added that it had paid out $4 billion to developers. In July 2011, it was at $2.5 billion.
Meanwhile, Google's Play Store continues to trail, but by most accounts is gaining. It has already caught the App Store in terms of the sheer number of apps, and is expected to pass one million apps in June, before the App Store.
However, when it comes to revenue, the App Store is far ahead. The Play Store is generating about 1/4 the revenue of the App Store. In terms of downloads, the Play Store passed 25 billion in late September.