Year Cases per 100,000 1990 3.24 1991 3.17 1992 3.1 1993 3.05 1994 2.99 1995 2.95 1996 2.9 1997 2.85 1998 2.81 1999 2.77 2000 2.74 2001 2.71 2002 2.69 2003 2.67 2004 2.66 2005 2.66 2006 2.64 2007 2.62 2008 2.61 2009 2.6 2010 2.58 2011 2.56 2012 2.53 2013 2.5 2014 2.48 2015 2.45 2016 2.42