Season 1968
NBC 
, 1968
Season 1971
NBC , 1971
Season 1972
NBC , 1972
Season 1973
NBC , 1973
Season 1974
NBC , 1974
Season 1975
NBC , 1975
Season 1976
NBC , 1976
Season 1977
ABC , 1977
Season 1978
ABC , 1978
Season 1989
ABC , 1989
Season 1990
ABC , 1990
Season 1991
ABC , 1991
Season 1992
ABC , 1992
Season 1993
ABC , 1993
Season 1994
ABC , 1994
Season 1995
ABC , 1995
Season 1997
ABC , 1997
Season 1998
ABC , 1998
Season 2001
ABC , 2001