Year Cases per 100,000 1990 2.63 1991 2.66 1992 2.68 1993 2.71 1994 2.74 1995 2.78 1996 2.81 1997 2.84 1998 2.88 1999 2.92 2000 2.96 2001 2.93 2002 2.91 2003 2.88 2004 2.85 2005 2.82 2006 2.8 2007 2.77 2008 2.75 2009 2.73 2010 2.71 2011 2.7 2012 2.7 2013 2.69 2014 2.68 2015 2.67 2016 2.67