AdMob has announced that they have hit a major milestone by serving 20 billion mobile ads, more than any other mobile ad company worldwide.

The graph below displays their growth. They have noted that the slight depression in February 2008 is due to the shortened month.

AdMob’s 20 billionth ad impression was from financial services conglomerate HDFC. The ad was served in India at 1:56am GMT on Tuesday, March 25, while a visitor was browsing Cricinfo’s mobile web site on a Nokia N70.

Some other information AdMob shared in their announcement:

• AdMob has an ad fill rate of 95% worldwide.
• AdMob has 40% market reach of U.S. Consumers with mobile browsing capabilities = 36 million folks.
• Over 3900 mobile websites use the AdMob platform.

More information on AdMob at http://www.admob.com.