Year Percent 1994 27.45807 1995 28.144 1996 26.89496 1997 24.89754 1998 23.17159 1999 23.18135 2000 24.70746 2001 25.78849 2002 27.1012 2003 29.10586 2004 29.22203 2005 29.10024 2006 28.61449 2007 32.0245 2008 29.40243 2009 24.84508 2010 25.78092 2011 26.46789 2012 26.32091 2013 25.6398 2014 26.55489 2015 24.25803 2016 23.89461 2017 22.49414