Facebook is undeniably the 800-pound gorilla of the social networking world, but at least one watcher thinks Google+ is going to give it a run for its money—and offers some numbers to back up the claim. Ancestry.com founder Paul Allen, a self-appointed “unofficial statistician” for Google+, claims the rise of Android and Google’s integration of Google+ into its other offerings is going to fuel user adoption of the social networking service—and while it may only have 60 million or so users now, Allen believes that number will explode to 400 million in just the next year.

“Based on the accelerated growth I’m seeing and all the dials and levers Google can still utilize, and the developer ecosystem that will be developed, I predict that 2012 is going to be a breakout year for Google+ and that it will end next year with more than 400 million users,” Allen wrote—appropriately enough—on Google+.

Google doesn’t reveal much about the number of users on Google+—back in October Larry Page announced the service had signed up more than 40 million users. Reports on Google+ adoption have been lackluster, with some industry watchers describing the service as a ghost town, thin on content and short on people—the same week Google crowed about 40 million users, others reported the service’s traffic was declining as it failed to hold on to users.

Given the lack of concrete user data from Google itself, Allen’s analysis of Google+ growth is based on queries for various surnames—Allen says his team from Elance has been tracking the same set of 337 surnames since July. According to Allen, nearly a quarter of all Google+ users—just over 24 percent—have signed up in December 2011 alone.

Allen also notes Google+ users upload five times as many photos a day than Facebook users—which may have something to do with instant-upload features baked into Android.