Year	Cases per 100,000
1990	3.2
1991	4.5
1992	6.4
1993	8.8
1994	11.9
1995	15.6
1996	19.7
1997	24
1998	28.1
1999	31.9
2000	35.1
2001	37.8
2002	39.8
2003	41.3
2004	42.4
2005	43.2
2006	43.9
2007	44.5