What percentage of the games you purchase do you actually complete?
By complete, I suppose I mean beating 100% of a title, unlocking all extras/completing all sidequests as well as the main game. Of course, you could interpret completing the game's Season or Story mode as completion too.
I complete about 15-20% of the games I buy 100%, simply because I prefer my games either lengthy or difficult, and fail to fully complete them as a result. I do, however, complete the main bulk of 90-95% of the games I play.