During his keynote address at the Apple Worldwide Developer Conference, CEO Steve Jobs said Apple now has 22% of the eBook market thanks to the iBookstore, which was introduced with the iPad and is now available for the iPhone and iPod touch.

Jobs says that users have downloaded more than five million books in the first 65 days of the iBookStore availability. That’s about 2.5 for each device sold—in the first 65 days of iBooks’ availability. The 22% figure is based on reports from five of the six largest publishers on the app’s share of their electronic sales.

When Apple announced the iPad, it also announced the new iBooks app for iPad, which includes Apple’s new iBookstore, a way to browse, buy and read books on a mobile device. And Apple has plans for the iBookstore beyond the US.