Year	Cases per 100,000
1990	0.5
1991	0.6
1992	0.8
1993	1
1994	1.3
1995	1.5
1996	1.7
1997	1.9
1998	2.1
1999	2.2
2000	2.3
2001	2.4
2002	2.4
2003	2.4
2004	2.4
2005	2.3
2006	2.3
2007	2.3