Year	Cases per 100,000
1990	0.9
1991	1.1
1992	1.1
1993	1.5
1994	1.8
1995	2.4
1996	3.4
1997	4.8
1998	6.9
1999	8.5
2000	9.5
2001	11
2002	12.6
2003	15.1
2004	17.6
2005	20.9
2006	24.1
2007	27.4