Year Cases per 100,000 1990 4.18 1991 4.17 1992 4.18 1993 4.19 1994 4.22 1995 4.25 1996 4.27 1997 4.28 1998 4.29 1999 4.23 2000 4.16 2001 4.08 2002 4.01 2003 3.96 2004 3.92 2005 3.86 2006 3.8 2007 3.77 2008 3.72 2009 3.66 2010 3.59 2011 3.53 2012 3.46 2013 3.41 2014 3.36 2015 3.3 2016 3.24