Year Cases per 100,000 1990 4.5 1991 4.46 1992 4.43 1993 4.4 1994 4.36 1995 4.33 1996 4.31 1997 4.28 1998 4.26 1999 4.24 2000 4.22 2001 4.16 2002 4.11 2003 4.05 2004 4 2005 3.95 2006 3.9 2007 3.85 2008 3.8 2009 3.75 2010 3.71 2011 3.71 2012 3.72 2013 3.73 2014 3.74 2015 3.75 2016 3.76