Year	Cases per 100,000
1980	17
1981	22
1982	18
1983	19
1984	15
1985	14
1986	15
1987	15
1988	15
1989	10
1990	7
1991	6
1992	4
1993	9
1994	10
1995	17
1996	18
1997	19
1998	19
1999	22
2000	15
2001	16
2002	13
2003	13
2004	17
2005	12
2006	11
2007	12