Season 1
6 episodes · 1971
Season 2
10 episodes · 1972
Season 3
10 episodes · 1973
Season 4
10 episodes · 1974
Season 5
10 episodes · 1975
Season 6
10 episodes · 1976
Season 7
10 episodes · 1977
Season 8
10 episodes · 1978
Season 9
10 episodes · 1979
Season 10
10 episodes · 1980
Season 11
10 episodes · 1981
Season 12
10 episodes · 1982
Season 13
10 episodes · 1983
Season 14
10 episodes · 1984
Season 15
10 episodes · 1985
Season 16
7 episodes · 1986
Season 17
29 episodes · 2011
Season 18
10 episodes · 2013