Year Percent 1994 25.85529 1995 25.7 1996 25.7 1997 25.21762 1998 27.43018 1999 24.35686 2000 19.36942 2001 19.06638 2002 17.78066 2003 19.15977 2004 20.5424 2005 21.31931 2006 20.93539 2007 21.68781 2008 23.15068 2009 22.83862 2010 22.39181 2011 22.12586 2012 21.54222 2013 22.23394 2014 22.06478 2015 22.54003 2016 23.16663 2017 23.37208