Year Cases per 100,000 1990 5 1991 5.5 1992 5.8 1993 6.2 1994 6.5 1995 6.9 1996 7.2 1997 7.8 1998 8.4 1999 9.1 2000 9.9 2001 10.7 2002 11.5 2003 12 2004 12.2 2005 12 2006 11.8 2007 11.5