I think my backlog is anywhere from 50-70% unplayed or unfinished.
Simply because I'm working most of the week and don't have enough time to play, and because I currently have the Saturn, NES and SNES pulled out/hooked up and most of those unplayed games are on PS1/PS2. And I don't currently feel like pulling the PS2 out of storage and hooking it up alongside 3-4 other sets of cables.