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