The folks at AdMob have just released their May 2009 Mobile Metrics Report… and, as per usual there is some great stuff to glean from their findings. This month, amongst all the other data and findings, they take a look at the distribution of users of the iPhone apps in their network as apposed to the typical percentage of ad requests. You can check out the handy chart above for yourself.
Keep in mind, this data is based on the 2,309 apps within the AdMob network in May, and all of the apps in their network are free. For that reason, AdMob is reluctant to shed any info on what the curve might look like for paid apps.
For more information you can download the May 2009 Mobile Metrics Report.
Note: As with all AdMob reports, results are from within their own network, not the iPhone network as a whole.