Year Cases per 100,000 1990 35.74 1991 35.29 1992 34.93 1993 34.6 1994 34.33 1995 34.13 1996 33.94 1997 33.74 1998 33.45 1999 33.59 2000 33.41 2001 33.41 2002 32.62 2003 31.85 2004 31.19 2005 30.71 2006 29.96 2007 29.16 2008 28.73 2009 27.83 2010 27.16 2011 26.29 2012 25.75 2013 25.25 2014 24.74 2015 24.28 2016 23.87