The Breaking Bad graph has all the markings of a fan favorite. The show had high ratings across the board–no single episode averaged lower than an 8–and a strong upward progression for each season. That last bit might be key to explaining the show’s success. By ending every season stronger than it started, Breaking Bad never left fans disappointed. In other words, while there may have been some clunkers in season three, generally speaking, people never felt like the show was losing steam.

Other graphs tell other stories. In the case of The Office, we see a strong climb in season three, just when the American version was finding its voice–and then a plateauing in seasons four and five, with a downward slide in season six. West Wing fell off after four seasons, when writer Aaron Sorkin left the show. 24 similarly lost steam after its first few seasons, only to come back with a riveting finale. Dexter was just the opposite, plummeting in its final season with a truly polarizing final episode.