Year Cases per 100,000 1990 4.4 1991 4.29 1992 4.19 1993 4.09 1994 4 1995 3.9 1996 3.81 1997 3.73 1998 3.64 1999 3.56 2000 3.48 2001 3.4 2002 3.32 2003 3.25 2004 3.18 2005 3.11 2006 3.21 2007 3.31 2008 3.42 2009 3.53 2010 3.65 2011 3.71 2012 3.77 2013 3.83 2014 3.9 2015 3.96 2016 4.03