Amazon.com has announced that for the first time ever, customers purchased more Kindle books than physical books on Christmas Day.

In addition, Amazon said its Kindle reader has become the most gifted item in the company's history. The Kindle Store boasts more than 390,000 electronic books.

"We are grateful to our customers for making Kindle the most gifted item ever in our history," said Jeff Bezos, founder and CEO of Amazon.com.

"On behalf of Amazon.com employees around the world, we wish everyone happy holidays and happy reading!"

Amazon has not released sales figures for the Kindle, but Forrester Research estimated in October that the Kindle has close to 60 percent of the U.S. market share, followed by the Sony Reader with 35 percent.

Amazon said its peak day was December 14, with customers ordering over 9.5 million items globally, which is a record breaking 110 items per second.

Amazon Worldwide 2009 Holiday Facts:

•     Amazon shipped to over 178 countries.
•     One of our most remote shipments contained the EMU Australia Toddler Boot and was delivered to   Atqasuk, Alaska.
•     On the peak day this season, Amazon's worldwide fulfillment network shipped over 7 million units.
•     Amazon shipped over 200,000 units to APO/FPO addresses.
•     Amazon shipped more than 99 percent of orders in time to meet holiday deadlines worldwide.