Valve has announced that their Steam service has seen over 100 percent sales growth for the seventh straight year. Last year, Steam offered over 1,800 games and had over 40 million registered accounts.

“Steam and Steamworks continues to evolve to keep up with customer and developer demands for new services and content,” said Gabe Newell, co-founder and president of Valve. “Support for in-game item trading prompted the exchange of over 19 million items. Support for Free to Play (FTP) games, launched in June, has spurred the launch of 18 FTP titles on Steam, with more coming in 2012. Looking forward, we are preparing for the launch of the Big Picture UI mode, which will allow gamers to experience Steam on large displays and in more rooms of the house.”

14.5 million copies of Steamworks games were registered during the year, and there are over 400 games that are part of the program. Steam also doubled content delivered during 2011 over last year by serving over 780 Petabytes of data, doubling its service capacity and adding a new content delivery architecture to improve user download rates and to meet demand.