Anyone who keeps up with gaming news knows that casual games are the biggest thing since sorted gems. But man, if a new report is to be believed, casual gaming is more popular than even we thought.

The report, from research firm Interpret, estimates that 145 million U.S. residents aged 12 to 65 played casual games in 2007. That's almost two-thirds of the roughly 222 million people in that age range. And just because they're casual games doesn't mean they're played casually -- the report estimates players spent an average of 5.1 hours per week on casual games in the fourth quarter of '07. That's nearly 740 million man hours spent playing casual games per week, outpacing activities like magazine and newspaper reading.

Even though most of these gamers only play games on free sites like EA's Pogo, Interpret still estimates industry revenues of $400 to $700 million by 2010. That's a drop in the bucket compared to estimates of $40 billion in total industry revenues by that point, but if we were a small developer, we sure we wouldn't mind having a piece of it.

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This article was originally published on Joystiq.