Year	Cases per 100,000
1990	0.3
1991	0.4
1992	0.5
1993	0.6
1994	0.8
1995	1
1996	1.3
1997	1.6
1998	1.9
1999	2.3
2000	2.7
2001	3.1
2002	3.4
2003	3.8
2004	4.1
2005	4.4
2006	4.6
2007	4.8