Year	Cases per 100,000
1990	15.2
1991	16.6
1992	16.5
1993	15.8
1994	14.9
1995	13.9
1996	13
1997	12.2
1998	11.3
1999	10.6
2000	9.8
2001	9.2
2002	8.6
2003	8
2004	7.5
2005	7
2006	6.5
2007	6.2