Year	Cases per 100,000
1990	0.4
1991	0.6
1992	1
1993	1.4
1994	2
1995	2.7
1996	3.6
1997	4.5
1998	5.4
1999	6.2
2000	6.8
2001	7.4
2002	7.8
2003	8.1
2004	8.2
2005	8.4
2006	8.5
2007	8.5