Year Cases per 100,000 1990 46.89 1991 45.69 1992 43.89 1993 42.41 1994 41.1 1995 40.16 1996 41.29 1997 39.49 1998 39.01 1999 36.47 2000 34.62 2001 33.26 2002 32.08 2003 31.03 2004 29.99 2005 28.08 2006 25.69 2007 23.94 2008 23 2009 23.53 2010 23.86 2011 23.01 2012 22.48 2013 22.77 2014 22.97 2015 23.12 2016 23.24