Year Cases per 100,000 1990 2.87 1991 2.87 1992 2.87 1993 2.87 1994 2.86 1995 2.86 1996 2.86 1997 2.86 1998 2.87 1999 2.85 2000 2.84 2001 2.85 2002 2.85 2003 2.85 2004 2.85 2005 2.85 2006 2.85 2007 2.84 2008 2.84 2009 2.85 2010 2.85 2011 2.87 2012 2.9 2013 2.92 2014 2.94 2015 2.96 2016 2.99