From the Overview Portion of the Report:
The share of adult cell phone owners who have downloaded an app to their phone nearly doubled in the past two years – rising from 22% in September 2009 to 38% in August 2011 – according to a new survey by the Pew Research Center’s Internet & American Life Project. The share of U.S. adults who purchased a phone already equipped with apps also increased five percentage points in the past year, from 38% in May 2010 to 43% in the current survey.
When both groups are accounted for—those whose phones came equipped with apps and those who have downloaded their own—fully half of U.S. adult cell phone owners (50%) now have apps on their phones. In May 2010, that figure stood at 43%. Looking at all U.S. adults, 42% now have cell phones with apps.
In addition to examining mobile app use on cell phones, the current survey included questions about mobile app use on tablet computers. It finds that among the 10% of adults who currently own a tablet, three-quarters (75%) report downloading apps to their tablet. This translates to 8% of all U.S. adults. The vast majority of tablet app downloaders (82%) have also downloaded apps to a cell phone, thus there is considerable overlap across the two groups.
Overall, when cell and tablet app downloaders are combined, 34% of adults report downloading apps to one or both of these devices.