Year	Cases per 100,000
1990	0.3
1991	0.4
1992	0.5
1993	0.7
1994	0.9
1995	1.2
1996	1.5
1997	2
1998	2.6
1999	3.4
2000	4.4
2001	5.7
2002	7.3
2003	9.4
2004	12.1
2005	15.4
2006	19.4
2007	23.1