Year Cases per 100,000 1990 5.23 1991 5.1 1992 5.04 1993 5.02 1994 4.89 1995 4.77 1996 4.55 1997 4.37 1998 4.22 1999 4.12 2000 4.03 2001 4.07 2002 4.11 2003 4.14 2004 4.17 2005 4.08 2006 4.01 2007 3.94 2008 3.87 2009 3.81 2010 3.74 2011 3.68 2012 3.62 2013 3.56 2014 3.5 2015 3.44 2016 3.38