SAN FRANCISCO: More than five million digital books have been downloaded since Apple began selling the iPad tablet computer two months ago, Apple chief executive Steve Jobs said.Jobs, in a keynote speech at Apple's Worldwide Developers Conference (WWDC) here, also said that the 8,500 applications developed for the iPad have been downloaded more than 35 million times from Apple's App Store.Jobs, dressed in his trademark black turtleneck and blue jeans, received a standing ovation as he walked on stage to address the more than 5,200 software developers attending the conference.Jobs is expected to unveil the next-generation iPhone at the event.Apple has sold more than two million iPads since the touchscreen device went on sale in the United States in early April and in nine other countries late last month.