Valve co-founder Gabe Newell has shared some surprising statistics about free to play title Team Fortress 2, revealing that its conversion of people playing for free to those spending real money is way above the average. "When we talk to partners who do free-to-play, a lot of people see about a 2 to 3 percent conversion rate of the people in their audience who actually buy something," Newell said at a recentWTIA TechNW panel. "With Team Fortress 2, which looks more like Arkham Asylum in terms of the user profile and the content, we see about a 20 to 30 percent conversion rate of people who are playing those games who buy something." In the online multiplayer game, players can purchase special equipment and apparel for their characters via microtransactions. Newell suggested that the type of content might be responsibile, but admitted they still had a lot to learn. "We don't understand what's going on. All we know is we're going to keep running these experiments to try and understand better what it is that our customers are telling us." "And there are clearly things that we don't understand because a simple analysis of these statistics implies very contradictory yet reproducible results. So clearly there are things that we don't understand, and we're trying to develop theories for them." The outspoken developer admitted it was "an exciting time but also a very troubling time." Valve recently announced that Team Fortress 2 community members had made $2 million by creating and selling virtual items via Team Fortress 2's Mann Co. Store.