Year Cases per 100,000 1980 39 1981 36 1982 33 1983 44 1984 12 1985 62 1986 13 1987 18 1988 12 1989 20 1990 17 1991 16 1993 15 1994 9 1995 25 1996 17 1997 15 1998 19 1999 20 2000 19 2001 20 2002 19 2003 20 2004 21 2005 25 2006 27 2007 27