Year Percent 1990 27.50161 1991 25.55719 1992 27.84554 1993 23.6848 1994 19.91674 1995 16.7658 1996 14.93711 2006 26.93256 2007 25.71282 2008 27.3742 2009 27.28605 2010 23.60443 2011 23.168 2012 26.62445 2013 25.60989 2014 25.79128 2015 24.68758 2016 20.84763