Year Cases per 100,000 1990 6.7 1991 10.4 1992 16 1993 23.5 1994 33 1995 43.9 1996 55.3 1997 66.1 1998 75.6 1999 83.4 2000 89.7 2001 94.8 2002 99 2003 102.5 2004 105.5 2005 108.3 2006 111 2007 113.7