Year Cases per 100,000 1990 1.31 1991 1.31 1992 1.3 1993 1.3 1994 1.3 1995 1.3 1996 1.3 1997 1.29 1998 1.29 1999 1.28 2000 1.28 2001 1.28 2002 1.28 2003 1.28 2004 1.28 2005 1.28 2006 1.28 2007 1.28 2008 1.28 2009 1.28 2010 1.29 2011 1.28 2012 1.27 2013 1.27 2014 1.27 2015 1.26 2016 1.26