Almost 217 million people worldwide visited online gaming Web sites in May 2007, according to comScore’s "World Metrix" report. That is up almost 17% from May 2006, and represents 28% of the total worldwide online population ages 15 and older.

Bob Ivins of comScore said, "The fact that these Web sites are pulling in over a quarter of the total worldwide Internet population shows what a global phenomenon gaming has become. The potential of the online gaming arena should be especially appealing for advertisers, as the average online gamer visits a gaming site nine times a month."

Not all sites were equally popular worldwide. Yahoo! Games was tops in North America, with 18.7 million unique visitors. In Europe, the same site was only the fourth most popular, with 8.6 million unique visitors. 

Via eMarketer