Year % 2008 10.2710287818937 2009 8.58312049678553 2010 7.33234907813833 2011 5.59280508440585 2012 5.10621026773848 2013 5.93276512911765 2014 5.22375545391187 2015 5.9061271414496 2016 7.08391549135575 2017 7.22493587241291 2018 5.81130293445234