Year Percent 2004 0.18598 2005 0.04978 2006 0.11676 2007 0.04589 2008 2.88491 2009 3.27573 2010 0.38897 2011 1.5666 2012 0.67551 2013 0.22265 2014 0.57165 2015 0.69613 2016 0.05921 2017 -0.81371