Year	Cases per 100,000
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0.1
1996	0.1
1997	0.4
1998	0.9
1999	2.2
2000	4.7
2001	8.1
2002	11.5
2003	13.9
2004	15.6
2005	16.6
2006	17.4
2007	18