Year Percent 2001 2.3951 2002 2.05562 2003 1.47199 2004 2.14026 2005 2.5091 2006 2.23065 2007 2.02619 2008 1.55616 2009 1.54793 2010 1.61923 2011 1.69312 2012 1.44387 2013 1.57701 2014 1.55884 2015 1.40692 2016 1.27846 2017 1.38213