2008: Clay Shirky, outlining the basic idea that would become his book Cognitive Surplus:

So how big is that surplus? So if you take Wikipedia as a kind of unit, all of Wikipedia, the whole project — every page, every edit, every talk page, every line of code, in every language that Wikipedia exists in — that represents something like the cumulation of 100 million hours of human thought. I worked this out with Martin Wattenberg at IBM; it’s a back-of-the-envelope calculation, but it’s the right order of magnitude, about 100 million hours of thought.

And television watching? Two hundred billion hours, in the U.S. alone, every year. Put another way, now that we have a unit, that’s 2,000 Wikipedia projects a year spent watching television. Or put still another way, in the U.S., we spend 100 million hours every weekend, just watching the ads. This is a pretty big surplus.

2010: Hillel Fuld, citing data from Peter Vesterbacka of Rovio, the Finnish company behind the hit game Angry Birds:

Another mind boggling statistic about Angry Birds, and you should sit down for this one, is that there are 200 million minutes played a day on a global scale. As Peter put it, that number compares favorably to anything, including prime time TV, which indicates that 2011 will be a big year in the shift of advertisers’ attention from TV to mobile.

Some math: 200 million minutes a day / 60 minutes per hour * 365 days per year = 1.2 billion hours a year spent playing Angry Birds.

Or, if Shirky’s estimate is in the right ballpark, about one Wikipedia’s worth of time every month.

Just a lighthearted reminder that, even if the lure of the connected digital world gets people to skimp on the Gilligan’s Island reruns, that doesn’t necessarily mean their replacement behaviors will be any more productive. They could instead bring an ever greater capacity for distraction and disengagement and slingshot precision.

Now, if you’ll excuse me, I have a couple more levels to get three stars on.

[Aside: Note that Angry Birds still has a long way to go to catch up to television: 200 billion hours a year vs. 1.2 billion hours. And the TV number is U.S. only, while the Angry Birds one is global.]