Year	Cases per 100,000
1990	3.2
1991	3.3
1992	3.4
1993	3.2
1994	3.2
1995	3.1
1996	3
1997	2.9
1998	2.8
1999	2.7
2000	2.6
2001	2.5
2002	2.5
2003	2.4
2004	2.4
2005	2.4
2006	2.4
2007	2.4