A new study has found that 12 percent of U.S. households now own an e-reader for electronic books, such as Amazon's Kindle or Barnes & Noble's Nook. The number has tripled from just one year ago, indicating that American book readers are warming to the e-book format.

The phone survey, which was published yesterday, was conducted in April and May by the Pew Internet and American Life Project.

According to the Associated Press, one explanation may be the increasing affordability of the devices: prices for e-readers have fallen rapidly over the past year, likely due to increased competition in the e-reader marketplace. Many “few frills” models are available for around the $100 mark today.

The survey also found that ownership of tablet computers such as the iPad and various Google-Android-based models, has doubled over the past year to eight percent of households. Tablet computers can also read e-books.

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, said the study's authors.

This is the first time since the Pew Internet Project began measuring e-reader use in April 2009 that ownership of this device has reached double digits among U.S. adults. The study was based on research data from telephone interviews conducted by Princeton Survey Research Associates International from April 26 to May 22, 2011, among a sample of 2,277 adults, age 18 and older.

Both e-book reader and tablet computer adoption levels among U.S. adults are still well below that of other tech devices that have been on the market longer, according to the study's authors. Cell phones are far and away the most popular digital device among U.S. adults today, followed by desktop and laptop computers, DVRs and MP3 players.

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