Year	Cases per 100,000
1990	0.2
1991	0.3
1992	0.4
1993	0.4
1994	0.5
1995	0.6
1996	0.7
1997	0.9
1998	1
1999	1.1
2000	1.3
2001	1.4
2002	1.6
2003	1.7
2004	1.8
2005	1.9
2006	2
2007	2.1