Laugh tracks usually have nothing to do with how funny a show's writing actually is, but studies regularly show that people have a more positive experience with TV comedies when they have a laugh track. I assume it's probably something parasocial.
Yeah it was easy for me, because I recall that I first watched it in 2013, and binging all 4 seasons that then existed in a pretty quick timeframe. So I knew it had to be pretty close one way or the other. It ended up extremely close to that "less than half of a season", with 12 out of 25 episodes of season 1 being in 2009.