At Pew Research, "E-book Reading Jumps; Print Book Reading Declines":
The population of e-book readers is growing. In the past year, the number of those who read e-books increased from 16% of all Americans ages 16 and older to 23%. At the same time, the number of those who read printed books in the previous 12 months fell from 72% of the population ages 16 and older to 67%.Continue reading.
Overall, the number of book readers in late 2012 was 75% of the population ages 16 and older, a small and statistically insignificant decline from 78% in late 2011.
The move toward e-book reading coincides with an increase in ownership of electronic book reading devices. In all, the number of owners of either a tablet computer or e-book reading device such as a Kindle or Nook grew from 18% in late 2011 to 33% in late 2012. As of November 2012, some 25% of Americans ages 16 and older own tablet computers such as iPads or Kindle Fires, up from 10% who owned tablets in late 2011. And in late 2012 19% of Americans ages 16 and older own e-book reading devices such as Kindles and Nooks, compared with 10% who owned such devices at the same time last year.