Lets see...
My systems include: NES, SNES, Genesis, Sega Saturn, Playstation 1 2 3, Gamecube, Dreamcast, and N64.
I didn't really keep count of all the games, but I can say its well over 100.
I always made it a point to beat one game before I buy another, so my completion percentage would probably be around 95%.
The only games I can think of that I could not beat were the Ninja Gaiden games. Not one single game....
Now, if you include my...ahem..."unofficial" copies, that would put me at about 3000 games. I have games I haven't even attempted to play yet.