Mark Walsh from MediaPost.com did an article citing a recent Pew Research Center study on apps.
Taken from the article :
he surge in mobile app use goes well beyond “Angry Birds.” Nearly four in 10 (38%) adult U.S. cell phone owners downloaded an app in August, up from 22% in September 2009. Counting in phones that come with pre-loaded apps, half of us now have apps on our phones, according to a new survey by the Pew Research Center’s Internet & American Life Project.
Among the 10% of Americans who own tablet computers, the proportion of app-downloaders rises to 75%, reflecting the heightened appeal of apps on the devices’ larger screens. About a third (34%) use apps both on mobile phones and tablets. But the study notes that having apps and using them are not the same thing.