January 1987 - June 1987
July 1986 - December 1986
January 1985 - June 1985
July 1983 - December 1984
November 1982 - June 1983
April 1982 - October 1982
January 1982 - March 1982
November 1981 - December 1981
March 1980 - October 1981
October 1976 - February 1980
July 1972 - September 1976