From the Pew Internet & American Life Project
The percent of U.S. adults with an e-book reader doubled from 6% to 12% between November 2010 and May 2011. Hispanic adults, adults younger than age 65, college graduates and those living in households with incomes of at least $75,000 are most likely to own e-book readers. Parents are also more likely than non-parents to own these devices.
Tablet computers have not seen the same level of growth among U.S. adults in recent months. In May 2011, 8% of adults report owning a tablet computer such as an iPad, Samsung Galaxy or Motorola Xoom. This is roughly the same percentage of adults who reported owning this kind of device in January 2011 (7%), and represents just a 3 percentage-point increase in ownership since November 2010. Overall, the highest rates of tablet ownership are among Hispanic adults and those with household incomes of at least $75,000 annually.