Year Cases per 100,000 1990 12.1 1991 15.3 1992 19.4 1993 24.6 1994 30.8 1995 35.2 1996 44.4 1997 52.1 1998 65.4 1999 73.4 2000 93.5 2001 103.7 2002 112.4 2003 113.9 2004 120.7 2005 133.8 2006 151.8 2007 169.6