Season 1 CBS , 1968 - 1969 Watch now Season 2 CBS , 1969 - 1970 Watch now Season 3 CBS , 1970 - 1971 Watch now Season 4 CBS , 1971 - 1972 Watch now Season 5 CBS , 1972 - 1973 Watch now Season 6 CBS , 1973 - 1974 Watch now Season 7 CBS , 1974 - 1975 Watch now Season 8 CBS , 1975 - 1976 Watch now Season 9 CBS , 1976 - 1977 Watch now Season 10 CBS , 1977 - 1978 Watch now Season 11 CBS , 1978 - 1979 Watch now Season 12 CBS , 1979 - 1980 Watch now