The rise of e-reading

Published 4/4/2012 Pew Internet One-fifth of American adults (21%) report that they have read an e-book in the past year, and this number increased following a gift-giving season that saw a spike in the ownership of both tablet computers and e-book reading devices such as the original Kindles and Nooks.1 In mid-December 2011, 17% of American adults had reported they read an e-book in the previous year; by February, 2012, the share increased to 21%.
Source

Full Report (PDF)