The Computer Entertainment Suppliers Association, a Japanese trade group, has estimated that piracy of video games for consoles such as Nintendo DS and PSP cost the gaming industry $41.5 billion between 2004 and 2009.
The numbers came from a research study done with the Tokyo University Baba Lab, which tabulated downloads of the top 20 Japanese games from 114 piracy sites.
The trade group and the Baba Lab said peer-to-peer sharing could make the total much higher.
The U.S. and China host 60 percent of the piracy sites, they said. The largest number of Internet users accessing the piracy sites were from U.S., while Japan had the second highest and China third.