Year	Cases per 100,000
1990	0.8
1991	1
1992	1.2
1993	1.5
1994	1.8
1995	2.2
1996	2.7
1997	3.2
1998	3.9
1999	4.8
2000	5.7
2001	6.8
2002	8.1
2003	9.5
2004	11.1
2005	12.8
2006	14.8
2007	17