May 31, 1980
July 31, 1980
September 30, 1980
October 31, 1980
November 30, 1980
October 31, 1981
December 29, 1981
December 31, 1981
June 30, 1982
August 31, 1982
September 30, 1982
December 31, 1982
March 31, 1983
November 30, 1983
May 31, 1984
September 16, 1984
December 31, 1984
May 31, 1985
June 30, 1985
July 31, 1985
September 30, 1985
December 31, 1985