Just because the survey information and results always fascinate me - I looked at what Pew Research Center has that might be more recent on Reading Habits - the above info-graph is dated 2011.
The rise of e-reading - April 2012
Note that the table of contents to the right for various sections of the report. Part 2 is The General Reading Habits of Americans - which contains the section on how many books people said they read in a year. Sample size/# of people they gave surveys to: 2,900+. (Quote below from General Reading Habits section.)
"In our December  survey, looking at the general population, 72% of Americans age 16 and older read at least one book in the past year in print; 16% read at least one e-book; 11% listened to at least one audiobook. The figures for adults 18 and older in that survey were the same, except it was 17% who had read an e-book. When we re-asked the question of adults 18 and older in a survey from January 20-February 19, 2012, the number of readers of e-books in the previous year had increased to 21%.
...Interestingly, though, the oldest readers are the most avid book consumers. The table below shows the average (mean) figure was 17 books that a typical American read in the past year. The median number (the midway point) was eight books. And those ages 65 and older who were readers had read the most books, on average."
Tossing this link in for librarians:
Young American = age 16-29.
Pew Research Center - Topics (a list of other survey/reports)