Here is a chart from gamerankings.com that shows the number of good games/bad games for each console.
As you can see, the Wii has a lot of shovelware and the majority of its good games come from Nintendo. Four of its good games are PS2/Gamecube ports.
It's funny (to me at least) that the PS3 has the best ratio of good to bad games.
Here is the Kotaku link: http://kotaku.com/385981/the-wii-has-many-many-crummy-games