Season 1 NBC , 1950 Season 2 NBC , 1952 Season 4 NBC , 1954 Season 5 NBC , 1954 - 1955 Season 6 NBC , 1955 - 1956 Season 7 NBC , 1956 - 1957 Season 8 NBC , 1957 Season 9 NBC , 1958 Season 10 NBC , 1959 - 1960 Season 11 NBC , 1960 - 1961 Season 12 NBC , 1961 Season 13 NBC , 1962 - 1963 Season 14 NBC , 1963 - 1964 Season 15 NBC , 1964 Season 16 NBC , 1965 Season 17 NBC , 1966 Season 18 NBC , 1967 Season 19 NBC , 1968 - 1969 Season 20 NBC , 1969 Season 21 NBC , 1970 Season 23 NBC , 1973 Season 24 NBC , 1974