Seasons 10 and 11 were very topical as well so not sure what you're getting at. They might not seem as topical now since we are 10 years removed, but they were at the time (guitar hero, Hilary Clinton campaigning).
The seasons that weren't topical were the very beginning before they moved to the one week timeframe for new episodes (season 1,2, etc). These were actually my favorites because they were much more focused on making funny episodes. Now and even during season 10 it seems like they'd decide on one thing they thought was funny, base an episode around it, and run the joke into the ground until it stops being funny.
The seasons that weren't topical were the very beginning before they moved to the one week timeframe for new episodes (season 1,2, etc). These were actually my favorites because they were much more focused on making funny episodes. Now and even during season 10 it seems like they'd decide on one thing they thought was funny, base an episode around it, and run the joke into the ground until it stops being funny.