Year Percent 1995 13.15 1996 13.83 1997 12.41 1998 12.03 1999 11.75 2000 11.11 2001 10.26 2002 9.63 2003 9.58 2004 9.65 2005 8.52 2006 9.02 2007 8.83 2008 8.07 2009 7.92 2010 7.69 2011 7.32 2012 8.49 2013 8.32 2014 8.17 2015 8.18 2016 7.67