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