Year	Cases per 100,000
1990	0.1
1991	0.3
1992	0.5
1993	1
1994	1.7
1995	2.8
1996	3.9
1997	4.8
1998	5.3
1999	5.5
2000	5.5
2001	5.4
2002	5.3
2003	5.2
2004	5
2005	4.8
2006	4.6
2007	4.4