A report from 2005 on Piracy. http://www.pcworld.com/article/id,120885-page,1/article.html
To summarize this article, about 1/3 of all software sold in the world is pirated. The worst offenders are Vietnam, Ukraine, China, and Zimbabwe, who all have more than 90% of software illegally. The lowest piracy amounts are the US at 21%, New Zealand at 23%, and the UK at 27%. So good for the US. A large percentage of pirated software is operating systems (Microsoft claims 20%-25% of Windows copies are pirated), so actual video game piracy isn't that bad. Especially in the US, although worldwide it is growing due to the growing market in countries like China, Vietnam, and Korea.
As a side note, this makes guigr's statement completely impossible. Only 33% of software worldwide is pirated, and it would have to be nearly 80% for his statement to have any validity, or at least nearly 80% in the US, where the majority of PC game sales come from.
