Amazon has revealed that readers are now buying more e-books than printed books. For every 100 hardback and paperback books sold on, the company also sells 114 Kindle books (not including free books).

It took four years for Amazon e-books to start outselling print books in the US, following the launch of the Kindle in 2007. However, this landmark has been hit after less than two years in the UK. Amazon launched its Kindle in the UK in August 2010.

The company's sales figures also show that people that own Kindles read more. Kindle owners in the UK bought four times the number of books they did prior to owning the device, as well as continuing to buy physical books.

The Kindle's success is largely due to the fact that it offers an electronic ink display which reads like real paper with no glare and downloading books only takes 60 seconds.

Free Kindle reading apps are also available for the most popular devices, including iPad, iPod touch, iPhone, PC, Mac and Android-based devices.

Over 2011 there has been more than a 400% increase in independent UK authors. This is because Kindle allows authors to self-publish through Kindle Direct Publishing (KDP) and earn up to 70% royalties from the books they sell.

“As a result of the success of Kindle, we’re selling more books than ever before on behalf of authors and publishers. And thanks to Kindle Direct Publishing, thousands of self-published authors have also been given an outlet to share their work with the millions of Kindle readers worldwide”, said Jorrit Van der Meulen, vice president of Kindle EU.

E.L. James is the best selling author in the Kindle Store at, having sold over two million Kindle books in just four months. Among the top 10 most popular authors of 2012 in the Kindle Store are three KDP authors: Nick Spalding, Katia Lief and Kerry Wilkinson.

Wilkinson is one of the world's most successful self-published authors, and has sold more than 300,000 copies of his work in the past year – even more than J.K. Rowling.

More than half a million Kindle books are priced at £3.99 or less. Many Kindle titles are a fraction of the price of printed books and some classics by Jane Austen and Charles Dickens are free.

Amazon says that it is not the end for physical books, however, and its print business continues to grow.