The AAP has been tracking ebooks since 2002. That year, ebooks represented 0.05% of all trade publishing revenues. To get to the current 23% number, the biggest gains were made in 2009, 2010 and 2011, the years immediately following the 2007 launch of the Kindle. In 2008, ebooks were 1% of publisher revenue. In 2011, they were 17%. Those were the years of triple-digit growth numbers, a trend publishers thought would continue until ebooks were at 50% of revenue or more.
But in 2012, according to these new numbers, growth in ebooks has hit an inflection point in the U.S.