Amazon is reporting that ebooks on the Kindle are now officially outselling paperback books. Since January 1st, for every one paperback book sold, fifteen ebooks were sold. In doing the math, this means Amazon is selling 13% more ebooks than paperback books. Kindle books have been outselling hardcover books since July of 2010, but this is the first time they have surpassed paperbacks. The data includes Amazon's entire book business in the U.S. and sales of books that don't have a digital version. It excludes free books.

Amazon has yet to release details on how many Kindles they sold in 2010, although some speculate it could be as much as eight million. Not including free books, Amazon stated there are now 810,000 ebooks available in the Kindle store. Amazon also recently released Kindle Singles, which are short stories or articles that can be purchased on the Kindle for as little as $0.99.