Apple today announced that over 15 billion apps have been downloaded from its App Store by the more than 200 million iPhone, iPad, and iPod touch users worldwide. The company also disclosed that it has paid developers over $2.5 billion to date.

The Apple App Store now offers more than 425,000 apps, over 100,000 of which are native iPad apps. iOS users in 90 countries can access the online store and download both paid and free apps in 20 categories.

"In just three years, the revolutionary App Store has grown to become the most exciting and successful software marketplace the world has ever seen," Philip Schiller, Apple's senior vice president of Worldwide Product Marketing, said in a statement. "Thank you to all of our amazing developers who have filled it with over 425,000 of the coolest apps and to our over 200 million iOS users for surpassing 15 billion downloads."

In April 2009, Apple announced it had seen over 1 billion apps downloaded. In April 2010, the company passed the 10 billion apps downloaded mark. Now, over a year later, 15 billion apps have been downloaded.

There's no arguing that the number of apps downloaded from the Apple App Store is growing, but this growth seems more or less steady. Google's Android Market meanwhile is seeing an accelerated growth in app downloads.

It took Google 20 months to reach the 1 billion apps installed on the Android platform. Five months later, the company had hit the 2 billion apps installed milestone. Two months later, in April 2011, the store hit the 3 billion apps milestone.

It's very possible that Google will start to see the number of installed apps slow down eventually. Right now, however, it doesn't look like that will happen anytime soon, especially given that search giant is activating 500,000 Android devices daily, as of last month. If the rates hold steady, Google will pass Apple in this respect next year, but between then and now, anything can happen.