September 1973 - May 1974
August 1972 - June 1973
September 1973 - October 1974
October 1974 - May 1975
May 1975 - September 1975
September 1975 - April 1976
April 1976 - October 1976
October 1976 - March 1977
March 1977 - August 1977
August 1977 - March 1978
March 1978 - July 1978
July 1978 - March 1979
April 1979 - October 1979
October 1979 - March 1980