Year	Cases per 100,000
1990	1.6
1991	2.3
1992	3.2
1993	4.4
1994	6
1995	7.8
1996	9.9
1997	12
1998	14.1
1999	15.9
2000	17.5
2001	18.9
2002	19.9
2003	20.7
2004	21.2
2005	21.6
2006	21.9
2007	22.3