Year % 2010 4.24664052157741 2011 4.00016076136015 2012 3.97136636161539 2013 3.68474668643624 2014 3.64473362976888 2015 4.28818093989301 2016 4.55842456604276 2017 4.80625264012661 2018 4.47240666716669 2019 4.60213145217644