Year Cases per 100,000 1990 4.9 1991 4.91 1992 4.92 1993 4.94 1994 4.95 1995 4.96 1996 4.84 1997 4.73 1998 4.62 1999 4.51 2000 4.4 2001 4.29 2002 4.18 2003 4.07 2004 3.97 2005 3.88 2006 3.75 2007 3.62 2008 3.5 2009 3.39 2010 3.28 2011 3.22 2012 3.16 2013 3.1 2014 3.05 2015 2.99 2016 2.94