Year	Cases per 100,000
1983	23.04
1984	19.99
1985	18.69
1986	18.58
1987	16.07
1988	16.88
1989	15.7
1990	15.99
1991	14.4
1992	13.87
1993	13.38
1994	12.65
1995	13.46
1996	11.33
1997	11.24