Year Cases per 100,000 1990 35.18 1991 35.05 1992 35.64 1993 36.22 1994 36.35 1995 35.87 1996 34.98 1997 33.86 1998 32.79 1999 31.8 2000 30.58 2001 29.11 2002 28.38 2003 27.81 2004 27.12 2005 26.43 2006 25.73 2007 25.27 2008 25.28 2009 25.6 2010 25.53 2011 25.1 2012 24.3 2013 23.36 2014 22.46 2015 22.07 2016 21.68