Year	Cases per 100,000
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0
1996	0
1997	0
1998	0.1
1999	0.3
2000	1
2001	1.5
2002	1.8
2003	2.1
2004	2.5
2005	2.8
2006	3.1
2007	3.5