Year Cases per 100,000 1990 19.68 1991 20.05 1992 20.23 1993 20.28 1994 20.07 1995 20.25 1996 20.01 1997 19.77 1998 19.43 1999 19.24 2000 18.87 2001 18.23 2002 17.87 2003 17.28 2004 17.21 2005 16.99 2006 16.64 2007 16.21 2008 15.86 2009 15.8 2010 15.16 2011 14.88 2012 14.44 2013 14.18 2014 14.24 2015 14.46 2016 14.66