Apple is an app-selling machine.

In January of this year, Apple said it had passed the three billion mark for the number of mobile applications downloaded from its iTunes App Store. Now, Apple says in a statement that Apple customers have downloaded more than 15 million apps from its iTunes App Store.

The massive jump shows the success of Apple's iPad, iPhone and iPod touch products, in that not only are customers buying them -- they are using them at an astounding increasing pace. Apple says it has more than 200 million iPad, iPhone and iPod touch users worldwide.

Apple's iTunes App Store has more than 425,000 free and paid apps available, 100,000 of which were designed specifically for the iPad. Many are interchangeable, usuable on all products

In just three years, the revolutionary App Store has grown to become the most exciting and successful software marketplace the world has ever seen, said Philip Schiller, Apple's senior voice president of Worldwide Product Marketing. 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.

Apple says apps have been sold to consumers in more than 90 countries around the world. Among the most popular paid apps available at Apple's iTunes App Store are games including Angry Birds (#1), Fruit Ninja (#2) and Tiny Wings (#3), which sell for 99 cents, while the most popular free apps include ICEE Maker (#1 in the entire app store), Gravity Guy (#2), and Talking Justin Bieber (#3).

App developers, of course, are pleased with Apple's success.

We sparked musical magic when iPhone users experienced Ocarina three years ago, said Dr. Ge Wang, a Smule co-founder and assistant professor at Stanford's Center for Computer Research in Music and Acoustics. And now with iPad, we've created the Magic Piano and Magic Fiddle apps. Who could've dreamt an iPad would make its way into the San Francisco Symphony?

To date, Apple has paid developers over $2.5 billion, the company says.