Complex sentence: Though the show finished last in the ratings in the first season, it was well received by critics, and ratings slowly but surely improved in 1983, and by 1986 "Cheers" was one of the top ten shows on TV.
Split into simpler sentences: Though the show finished last in the ratings in the first season, it was well received by critics and ratings slowly but surely improved in 1983. By 1986 "Cheers" was one of the top ten shows on TV.