Year Cases per 100,000 1990 11 1991 15.4 1992 19.9 1993 24.9 1994 29.9 1995 35.1 1996 39.7 1997 44.9 1998 50.2 1999 55.9 2000 61.9 2001 67.8 2002 72.9 2003 76.4 2004 77.3 2005 76.5 2006 74.6 2007 72.7