Year	Cases per 100,000
1990	7.3
1991	8
1992	8.2
1993	8
1994	7.7
1995	7.4
1996	7.2
1997	7
1998	6.8
1999	6.7
2000	6.6
2001	6.5
2002	6.5
2003	6.5
2004	6.5
2005	6.5
2006	6.5
2007	6.5