1977 December 5 1978 April 24 1979 March 12 1979 April 10 1981 January 19 1984 April 26 1985 November 15 1986 October 10 1986 October 13 1988 April 3 1988 July 8 1989 February 9 1989 March 5 1989 April 21 1989 April 24 1989 May 25 1989 September 1 1989 September 3 1990 March 27 1991 May 16 1991 June 2 1991 June 10 1994 March 6 1994 May 30 1995 May 18 1996 May 16 1998 September 27 1998 October 16 1998 October 18 1999 June 11 1999 June 14 2001 June 28 2001 September 16 2002 April 19 2002 April 24 2003 July 7 2005 April 19 2005 July 29 2006 April 21 2006 June 12 2006 October 12 2009 June 3 2009 December 9 2010 December 21 2011 May 16 2014 June 12 2015 October 15