1978 February 16 1979 February 8 1979 February 22 1980 March 20 1981 November 19 1983 September 22 1984 August 28 1984 September 20 1986 October 3 1986 October 7 1986 November 11 1989 February 14 1989 September 8 1991 June 5 1993 February 22