Year Percent 1994 22.78268 1995 22.39362 1996 21.68976 1997 20.93638 1998 20.18714 1999 18.09763 2000 16.99378 2001 16.08834 2002 16.87394 2003 16.74548 2004 15.70174 2005 16.51704 2006 17.18591 2007 18.12522 2008 18.16357 2009 15.93046 2010 16.54994 2011 16.69128 2012 15.96453 2013 15.56236 2014 15.50284 2015 15.60888 2016 16.20333