Many of us scoff at the notion of spending real-world cash on in-game purchases for freemium games, but the percentage of folks making those sorts of in-game purchases is higher than one might think. According to a report from the NPD Group, forty percent of those who play upgradeable freemium games have made in-game purchases.

The report also notes that although female gamers are more likely to play freemium games, male gamers are still the ones more likely to make in-app purchases for those types of titles. Those choosing to pay for such upgrades, typically do so within the first month of playing a game. Furthermore, 38 percent of the U.S. population--that's older than age 2--is reportedly playing "some type of freemium game."

"Males and those ages 18 to 34 are traditionally seen as a big part of the core gamer audience, so it's likely these groups are not quite as engaged with freemium because the gaming experience is quite different from what they are used to from the games they play on consoles, handhelds or PCs," said industry analyst Anita Frazier. "At a minimum, for these gamers a freemium game would provide a different experience, like a snack versus a full meal."

The data about freemium gaming habits was collected during a March study of 6,416 individuals, ages 2 and older.