http://biz.gamedaily.com/features.asp?article_id=10650&filter=
According to a Telephia study, 36 percent of mobile games were free to download. Unsurprisingly, puzzle and strategy games have the largest market share, with a 27 percent share of revenue and a 48 percent share of all free downloads. A second study sponsored by I-play indicates that American gamers are more likely to show off their mobile games to friends and are more competitive about gaming than their European counterparts.