Year Cases per 100,000 1990 25.39 1991 25.56 1992 25.75 1993 25.94 1994 26.13 1995 26.34 1996 25.94 1997 25.57 1998 25.2 1999 24.85 2000 24.51 2001 23.86 2002 23.24 2003 22.64 2004 22.06 2005 21.51 2006 21.23 2007 20.93 2008 20.65 2009 20.38 2010 20.13 2011 19.97 2012 19.83 2013 19.69 2014 19.55 2015 19.41 2016 19.29