Year Cases per 100,000 1990 7.98 1991 7.91 1992 7.84 1993 7.78 1994 7.72 1995 7.66 1996 7.3 1997 6.97 1998 6.66 1999 6.36 2000 6.08 2001 5.75 2002 5.44 2003 5.15 2004 4.88 2005 4.62 2006 4.42 2007 4.22 2008 4.03 2009 3.85 2010 3.68 2011 3.63 2012 3.58 2013 3.53 2014 3.49 2015 3.44 2016 3.4