Year	Cases per 100,000
1990	4.3
1991	5
1992	5.8
1993	6.5
1994	7.2
1995	7.9
1996	8.4
1997	8.9
1998	9.3
1999	9.5
2000	9.6
2001	9.6
2002	9.5
2003	9.4
2004	9.2
2005	9
2006	8.7
2007	8.4