Year	Cases per 100,000
1990	1.6
1991	2.1
1992	2.7
1993	3.5
1994	4.4
1995	5.5
1996	6.7
1997	8.2
1998	9.8
1999	11.5
2000	13.4
2001	15.4
2002	17.5
2003	19.6
2004	21.7
2005	23.7
2006	25.8
2007	27.7