Year Cases per 100,000 1990 32.94 1991 33.12 1992 33.17 1993 33.44 1994 33.31 1995 33.21 1996 32.82 1997 32.27 1998 31.75 1999 30.46 2000 29.78 2001 29.19 2002 28.62 2003 27.96 2004 27.35 2005 27.13 2006 27.05 2007 26.73 2008 26.43 2009 26.09 2010 25.82 2011 25.25 2012 24.83 2013 24.41 2014 24.02 2015 23.53 2016 23.15