Year	Cases per 100,000
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0
1996	0
1997	0.1
1998	0.3
1999	0.8
2000	1.9
2001	4
2002	5.9
2003	6.9
2004	7.1
2005	6.8
2006	6.6
2007	6.3