Year Percent 2005 0.97402 2006 0.80691 2007 0.54992 2008 0.44923 2009 0.52148 2011 0.3586 2012 0.32803 2013 0.42187 2014 0.35699 2015 0.47336 2016 0.58623 2017 0.58112