Year Cases per 100,000 1990 2.23 1991 2.23 1992 2.24 1993 2.24 1994 2.25 1995 2.25 1996 2.26 1997 2.26 1998 2.27 1999 2.27 2000 2.28 2001 2.28 2002 2.28 2003 2.28 2004 2.28 2005 2.28 2006 2.28 2007 2.27 2008 2.27 2009 2.27 2010 2.27 2011 2.26 2012 2.25 2013 2.25 2014 2.24 2015 2.24 2016 2.23