Year	Cases per 100,000
1990	0.6
1991	1
1992	1.6
1993	2.5
1994	3.5
1995	4.4
1996	5
1997	5.4
1998	5.7
1999	5.9
2000	6.1
2001	6.3
2002	6.5
2003	6.7
2004	6.9
2005	7.1
2006	7.3
2007	7.6