Global ad network AdMob has released their latest mobile metrics report, which analyzes the over 8 billion ad requests that AdMob receives each month.

The report indicates that close to half of all iPhones are now located outside the US. It also indicates that requests from Android phones have grown 25% since last month, and are now ahead of Microsoft Windows Mobile.

According to AdMob, in June, 54% of iPhone and iPod touch users were in the US. In January 2009 this percentage was 61% , indicating that international user growth has outpaced US user
growth.

AdMob has also used public statements from Apple about total shipment numbers for iPhone and iPhone Touch to estimate the total installed base of iPhone O/S devices in each market.

The report also includes extensive information about the geographic distribution and growth rate for AdMob ad reqeusts, as well as handset and operator information for several countries, including US, UK, India, Indonesia, Philippines, and South Africa.