Year	Cases per 100,000
1990	0
1991	0
1992	0.1
1993	0.2
1994	0.3
1995	0.6
1996	1
1997	1.4
1998	1.8
1999	2.2
2000	2.3
2001	2.1
2002	2
2003	2
2004	2.1
2005	2.1
2006	2.1
2007	2.2