Year	Cases per 100,000
1990	0.2
1991	0.2
1992	0.2
1993	0.3
1994	0.4
1995	0.4
1996	0.5
1997	0.6
1998	0.8
1999	0.9
2000	1
2001	1.2
2002	1.3
2003	1.4
2004	1.6
2005	1.7
2006	1.8
2007	1.9