Year	Cases per 100,000
1990	0.3
1991	0.5
1992	1
1993	2
1994	3.5
1995	5.5
1996	7.8
1997	9.5
1998	10.6
1999	11
2000	11
2001	10.8
2002	10.6
2003	10.4
2004	10
2005	9.6
2006	9.2
2007	8.8