Year Cases per 100,000 1990 23.47 1991 22.83 1992 21.55 1993 20.79 1994 19.53 1995 17.83 1996 17.09 1997 16.85 1998 17.63 1999 17.67 2000 17.85 2001 17.47 2002 18.83 2003 20.33 2004 21.21 2005 22.4 2006 23.06 2007 23.12 2008 23.29 2009 23.6 2010 23.72 2011 23.99 2012 23.86 2013 23.32 2014 22.8 2015 22.21 2016 21.7