Year Cases per 100,000 1990 4.49 1991 4.47 1992 4.47 1993 4.46 1994 4.46 1995 4.46 1996 4.43 1997 4.4 1998 4.38 1999 4.36 2000 4.34 2001 4.28 2002 4.23 2003 4.18 2004 4.13 2005 4.08 2006 4.02 2007 3.95 2008 3.89 2009 3.83 2010 3.78 2011 3.77 2012 3.76 2013 3.76 2014 3.75 2015 3.75 2016 3.74