Year	Cases per 100,000
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0
1996	0
1997	0.1
1998	0.2
1999	0.3
2000	0.4
2001	0.6
2002	0.8
2003	1.1
2004	1.3
2005	1.5
2006	1.7
2007	1.8