Apple's App Store annual revenue estimated at $2.4B

The latest Mobile Metrics Report from AdMob for July 2009 shows that iPhone users download an average of 10.2 applications from the App Store per month, with 2.6 of those paid. However, iPod touch users appear to be more app-hungry, downloading an average of 18.4 each month, with two paid.

Most users surveyed paid for their applications after upgrading from a "lite" version of the same application, suggesting most prefer to try before they buy. The average iPhone user spend $9.49 per month on the App Store, bringing in $125 million from the 26.4 million user install base in total revenue each month. Comparatively, the 18.6 million iPod touch users spend an average of $9.79 each month, capturing $73 million in sales.

The survey also found that the Android Marketplace is popular as well, with users downloading an average of 9.1 new applications per month. However, Android users are reportedly less likely to open their wallets, as the average user buys only one application per month, and only 19 percent of users buy paid apps.

Android's total presence in the market ballooned 53 percent during the period, bringing it to an estimated 7 percent worldwide OS share, and the Nokia N97 debuted as the ninth most popular handset in the U.K. Total worldwide mobile access increased 17 percent month over month, hitting 9.7 billion.

No matter the platform, more than 90 percent of those who download applications to their phone do it directly on the phone, rather than transferring over from the computer. The survey was based on over 1,000 iPhone, iPod touch and Android users.

Last month's Mobile Metrics Report found that more than half of all iPhone and iPod touch users worldwide were from the U.S., but predicted international growth was outpacing stateside sales.