"From the beginning Nintendo has wanted to attract non-traditional gamers with its Wii hardware and software. Perhaps as a result of the manufacturer's strategy, many Wii games have been designed to appeal to -- and therefore are rated for -- a general audience.
Over 82% of the Wii catalog is either rated E or E10+. Only 3.2% are rated M, less than half the rate on Nintendo's previous console, GameCube. Still, that 3.2% is significantly higher than the rates on either the Nintendo DS or the Game Boy Advance."
Xbox 360 M rated = 17.6%
PS3 M rated = 21%