My K/D from my "Most Recent 20" is 2.75 with a 257spm.
My overall is 0.94, but that includes long stretches of pure goofing off with snipers and shottys for the lawls. I'm kinda amazed by that, because in MW3, I was in full "try hard" mode early on, and my K/D was 0.72 for the longest time because my beast mode clicked on.
CoD 4: ~1.8 WAW: Too laggy for me, traded it in after a week. Probably ~1.2 MW2: ~1.6 BO: ~1.2, didn't really play much MW3: ~1.3, only played for a couple weeks BO2: 1.21
I estimated every other game because I don't have access to the actual numbers. CoD4 and MW2 are accurate for sure, though. I don't play in parties and have no friends who play the game, so I'm pretty much alone in most random games. W/L is .82.