Year	Cases per 100,000
1990	0.1
1991	0.2
1992	0.2
1993	0.3
1994	0.4
1995	0.5
1996	0.6
1997	0.8
1998	1
1999	1.1
2000	1.3
2001	1.5
2002	1.7
2003	1.9
2004	2
2005	2.2
2006	2.3
2007	2.4