hell yeah- I'd say they jumped the shark around season 7-that would have been 1996, I believe. Definitely by 1997. I can only bear to watch Treehouse of Horror now, and even that is approaching lameness. Last night's was worth it to hear the Perfect Strangers' theme though!!
I think it's gone downhill a number of times. What happens (as I see it) is the show declines in quality, then they hire a new gang of writers and the quality spikes upward...then the new writers cycle through or just run out of steam and the show goes down again. And so on. The problem is that with each "rebound" in quality, the highpoint is lower than the previous one. So what we have is a diminishing sine-wave. Just my impression. I barely catch the show anymore, though I watched the latest Treehouse of Horror last night. To be fair, seasons 2, 3, and (most of) 4 are a tough act to follow.
D'oh!