Cavalary: Not really off in my case. May even be optimistic.
Looking at my posts in the games finished threads... Finished 3 so far this year (+2 quick mobile ones, meh), should be about to finish another one now. Last year it was 2 in full and the base game of a 3rd (technically the expansion this year, so counted it for this year) (not counting a few quick browser games made during the massive protests that were here then - went through a couple more like that this year too). 5 in 2016, 6 if you count the base game and expansion of one separately. 3 in 2015, 4 in case of the same base / additional content separate count, 5 if you add a few quick games of another that doesn't have something to "finish". 5 in 2014, 6 if you count quite a bunch of "games" in a browser thingy, 6 if you also count a very short thing that isn't really a game. 1, 2 if you count its parts separately, in 2013, 3 if you also count a quick browser thingy. 5 in 2012. 3, 4 with that same base / expansion separate count, in 2011...
In terms of number of finished games I guess it is about the same with me.
But I think the first reason I buy games is to get familiar with them firsthand, provided the initial impression got me interested. Unfortunately I have been unable to find any metric that would tell me beforehand if I'd actually like a game or not. All reviews are different; summary scores are different from different sources; popularity, developer or publisher name, completion rates, even demos - nothing. And even if in some miraculous case most of those align, my own experience can easily differ.
So I expect to actually enjoy only a part of I bought, and finish a much smaller part still of course. But I came to realize I have to find out which is which by myself, not by some proxy.