Year Cases per 100,000 1980 0 1981 67 1982 0 1983 0 1984 0 1985 127 1986 0 1987 575 1988 64 1989 0 1990 62 1991 63 1992 64 1994 0 1995 135 1996 0 1999 0 2000 0 2001 0 2003 0 2005 0 2006 0 2007 0