Year Cases per 100,000 1990 6.5 1991 13.7 1992 26.3 1993 46.3 1994 72.3 1995 99.9 1996 123.5 1997 146.9 1998 170 1999 193.8 2000 207.8 2001 217.1 2002 231.2 2003 239.7 2004 242.8 2005 241.3 2006 240.8 2007 240.4