Year	Cases per 100,000
1980	12
1981	12
1982	11
1983	10
1984	9
1985	9
1986	9
1987	9
1988	9
1989	9
1990	10
1991	10
1992	10
1993	9
1994	9
1995	8
1996	8
1997	7
1998	7
1999	6
2000	6
2001	6
2002	5
2003	5
2004	5
2005	5
2006	5
2007	4