Year	Cases per 100,000
1980	15
1981	14
1982	14
1983	13
1984	13
1985	11
1986	10
1987	9
1988	9
1989	9
1990	10
1991	10
1992	9
1993	8
1994	10
1995	11
1996	9
1997	9
1998	10
1999	12
2000	9
2001	10
2002	8
2003	10
2004	9
2005	8
2006	8
2007	7