Year	Cases per 100,000
1990	16.4
1991	22.7
1992	26.8
1993	29.7
1994	31.2
1995	31.8
1996	31.8
1997	31.3
1998	30.5
1999	29.5
2000	28.4
2001	27.1
2002	26.1
2003	25.3
2004	24.8
2005	24.6
2006	24.2
2007	24.2