Year Percent 1995 49.34583 1996 55.26713 1997 54.78709 1998 48.52829 1999 52.08642 2000 49.77767 2001 49.85355 2002 52.74043 2003 53.4812 2004 50.7068 2005 51.1443 2006 45.25597 2007 47.45246 2008 40.81904 2009 36.87212 2010 39.22522 2011 44.97096 2012 43.48292 2013 43.34395 2014 41.53324 2015 42.80453 2016 43.33028 2017 42.53796