Year Cases per 100,000 1990 39.76 1991 37.8 1992 36.08 1993 35.69 1994 35.1 1995 34.29 1996 32.82 1997 31.16 1998 29.87 1999 28.45 2000 27.26 2001 26.3 2002 25.09 2003 24.31 2004 23.73 2005 23.03 2006 22.32 2007 21.53 2008 20.76 2009 20.54 2010 20.07 2011 19.55 2012 19.32 2013 18.89 2014 18.33 2015 18.09 2016 17.93