Year Percent 1994 34.70301 1995 34.41468 1996 34.4996 1997 34.11013 1998 33.54739 1999 33.03947 2000 32.75826 2001 31.26985 2002 30.53965 2003 30.4154 2004 30.29861 2005 30.19939 2006 29.98259 2007 29.8825 2008 29.00529 2009 27.27247 2010 28.44461 2011 26.88171 2012 26.74805 2013 26.93763 2014 27.68806 2015 28.89782 2016 29.30046