Year Cases per 100,000 1990 28.5 1991 37.5 1992 47.5 1993 57.6 1994 65.9 1995 71.4 1996 75.5 1997 77.4 1998 78.1 1999 77.2 2000 74.7 2001 70.9 2002 65.9 2003 59.9 2004 53.5 2005 47.5 2006 42.6 2007 38.5