Year Cases per 100,000 1990 20.52 1991 20.73 1992 20.92 1993 21.07 1994 21.22 1995 21.4 1996 21.72 1997 22.24 1998 21.98 1999 21.43 2000 20.86 2001 19.85 2002 19.01 2003 18.34 2004 17.65 2005 16.97 2006 16.92 2007 16.77 2008 16.63 2009 16.48 2010 16.37 2011 16.2 2012 16.06 2013 15.91 2014 15.76 2015 15.71 2016 15.65