Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

1970

N/A

N/A

YES

N/A

N/A

N/A

YES

YES

N/A

YES

N/A

N/A

1971

YES

YES

N/A

YES

YES

YES

YES

YES

YES

YES

N/A

N/A

1972

N/A

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

1973

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

1974

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

1975

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

N/A

YES

1976

YES

YES

YES

YES

YES

YES

YES

N/A

YES

N/A

N/A

YES

1977

YES

YES

YES

YES

YES

YES

YES

N/A

YES

YES

YES

N/A

1978

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

1979

YES

N/A

YES

YES

YES

YES

YES

YES

YES

YES

N/A

YES