So 1.8% of Wii owners downloaded New Super Mario Bros. Wii, and 2.7% of 360 owners downloaded Modern Warfare 2.
Looks like the real piracy problem is on the XBox. Either way, it can't be that bad when your piracy rate is lower than your hardware failure rate.
The real problem is the PC pirates, who get all political and pick specific games to boycott (and then download) like Spore and Modern Warfare, to protest the DRM or the lack of servers.