Year Cases per 100,000 1990 2.8 1991 2.8 1992 2.79 1993 2.79 1994 2.78 1995 2.79 1996 2.79 1997 2.79 1998 2.79 1999 2.79 2000 2.79 2001 2.76 2002 2.73 2003 2.7 2004 2.68 2005 2.65 2006 2.65 2007 2.64 2008 2.64 2009 2.64 2010 2.64 2011 2.64 2012 2.65 2013 2.65 2014 2.65 2015 2.64 2016 2.64