Year Cases per 100,000 1990 3.5 1991 4.1 1992 4.7 1993 5.3 1994 5.9 1995 6.5 1996 7.1 1997 7.6 1998 8.1 1999 8.5 2000 8.8 2001 9 2002 9.2 2003 9.3 2004 9.3 2005 9.3 2006 9.2 2007 9.2