Year Cases per 100,000 1990 20.41 1991 20.2 1992 20 1993 19.89 1994 19.29 1995 19.4 1996 19.73 1997 19.96 1998 20.46 1999 20.23 2000 20.04 2001 20.03 2002 19.99 2003 19.85 2004 19.69 2005 19.46 2006 19.27 2007 18.56 2008 18.31 2009 18.25 2010 17.77 2011 17.7 2012 18.43 2013 18.02 2014 17.89 2015 17.77 2016 17.69