Year	Cases per 100,000
1990	3.1
1991	4.4
1992	6
1993	8.1
1994	10.5
1995	13.2
1996	15.9
1997	18.6
1998	20.9
1999	22.9
2000	24.4
2001	25.5
2002	26.3
2003	26.8
2004	27.2
2005	27.4
2006	27.6
2007	27.7