Year	Cases per 100,000
1980	33
1981	31
1982	25
1983	26
1984	23
1985	27
1986	22
1987	18
1988	21
1989	21
1990	18
1991	20
1992	24
1993	22
1994	28
1995	20
1996	21
1997	30
1998	25
1999	25
2000	27
2002	14
2003	12
2004	17
2007	14