Android sales continue to snowball. In early December, Android chief Andy Rubin tweeted that Google is now activating about 300,000 Android handsets per day, compared with 60,000 a day at the beginning of the year. Two reasons for Android's ongoing success: Cameras that range between 5 and 8 megapixels and recorders capable of capturing video at 720p HD resolution. In addition, Google has attracted a growing stable of developers to its App Market. In March, there were more than 30,000 apps for Android; in December 2009, there were 16,000, Google said. Of these, about 39% of applications are paid for and 61% of applications are free, according to AndroLib estimates.