Year Percent 1994 19.76264 1995 20.09052 1996 20.00962 1997 19.43649 1998 19.23264 1999 20.26065 2000 20.15533 2001 21.49934 2002 21.46228 2003 20.59476 2004 21.39699 2005 20.96656 2006 20.8761 2007 20.72706 2008 21.96423 2009 21.07566 2010 21.96871 2011 23.1571 2012 24.54769 2013 25.38761 2014 25.09845 2015 24.50686 2016 24.28908 2017 23.62974