Year Cases per 100,000 1990 5.8 1991 5.81 1992 5.82 1993 5.82 1994 5.83 1995 5.85 1996 5.49 1997 5.16 1998 4.85 1999 4.56 2000 4.29 2001 4.18 2002 4.07 2003 3.96 2004 3.86 2005 3.76 2006 3.7 2007 3.64 2008 3.59 2009 3.53 2010 3.48 2011 3.52 2012 3.57 2013 3.61 2014 3.66 2015 3.71 2016 3.76