Year Cases per 100,000 1983 33.81 1984 35.16 1985 35.87 1986 37.5 1987 35.27 1988 34.47 1989 34.74 1990 35.45 1991 35.31 1992 36.45 1993 35.82 1994 38.32 1995 39.21 1996 40.93 1997 38.86