http://www.pcgamer.com/2012/08/22/pc-gaming-has-around-a-93-95-per-cent-piracy-rate-claims-ubisoft-ceo/
Ubisoft CEO Yves Guillemot has been speaking to GamesIndustry International about Ubi’s reasons for embracing the free to play model. He says free to play games are more cost effective to create because typical PC releases are so heavily pirated. He claims that “only about five to seven per cent” of players pay for PC games, “the rest is pirated.”
Guillemot doesn’t provide any evidence for this, but insists that the rate of paying customers for a traditional release is equal to that of a free to play game. He says that the free to play model lets Ubisoft “take content which we’ve developed in the past, graphics etc,” to make “cheaper games and improve them over time.”
It could be 0% and they would still be going F2P if it is more profitable.
Meanwhile, in the real world...
http://portal.bsa.org/globalpiracy2011/