Like 2008, before it went HD. I was getting tired of it a while before that, but it wasn't like watching one new episode each week was a huge time investment either.
But then once I became too busy to catch the new episode premieres live I just stopped keeping up with it entirely, since I wasn't getting anything out of it anymore and now I didn't even have the excuse of not doing anything more important when it was on.
I'm still at least peripherally aware of what the show's doing, because it's like I'm curious just to see how weird/bad it'll get but not curious enough to commit to following it. One day I might actually get curious enough to try to watch the entire show in order (no, not in one sitting) and see exactly what I missed, but it's not gonna happen anytime soon.