Year	Cases per 100,000
1990	0.2
1991	0.3
1992	0.4
1993	0.5
1994	0.6
1995	0.7
1996	0.8
1997	0.9
1998	1
1999	1
2000	1
2001	1.1
2002	1.1
2003	1.1
2004	1.1
2005	1
2006	1
2007	1