About 34 percent of U.S. adults ages 18 and older own a tablet computer like an iPad, Samsung (News - Alert) Galaxy Tab, Google Nexus or Kindle Fire, up nearly 100 percent, year over year.

In 2012, about 18 percent of respondents surveyed by the Pew (News - Alert) Internet and American Life Project owned a tablet.

As you might guess, there are differences in rates of adoption, as there were with smartphones.

As was true for Apple (News - Alert) iPhone owners, households with higher incomes are more likely to be tablet owners. About 56 percent of households earning at least $75,000 per year own tablets, compared to 38 percent of people in households earning between $50,000 and $74,999.

About 28 percent of respondents in households with $30,000 to $49,999 in income own tablets, compared to 20 percent of respondents in households below $30,000 annual household income.

Unlike smartphones, which are most popular with younger adults ages 18 to 34, the highest rates of tablet ownership occur among adults 35 to 44. In that age bracket, 49 percent of respondents report owning a tablet.

In the 25 to 34 age bracket, 37 percent of respondents own a tablet. About 18 percent of adults ages 65 and older are less likely to own a tablet.

Tablet adoption, as did iPhone (News - Alert) adoption, is directly related to education. About 49 percent of adults with at least a college degree own a tablet. Only 17 percent of those who did not graduate high school own a tablet.

The findings might suggest that smart phones are “mission critical” devices, while tablets are more discretionary.

"With smartphones, for instance, we’ve seen a very strong correlation with age where most younger adults own smart phones, regardless of income level,” said Research Analyst Kathryn Zickuhr. “But when it comes to tablets, adults in their thirties and forties are now significantly more likely than any other age group to own this device."