Year Cases per 100,000 1990 7.1 1991 10 1992 13.6 1993 18.1 1994 23.4 1995 29.8 1996 36.7 1997 44.8 1998 53.8 1999 63.7 2000 74.3 2001 84.8 2002 94.4 2003 101.6 2004 104.9 2005 105.4 2006 103.9 2007 102.1