Year % 2006 2.73942939162815 2007 2.24246731582086 2008 1.90306942802894 2009 2.25042258658752 2010 2.83071715205898 2011 2.70681550509306 2012 2.81336476630545 2013 2.86654169526513 2014 3.47337431453068 2015 3.39283728404187 2016 2.69521741465076 2017 2.36889544229069 2018 1.88242856429559 2019 1.62862135995416 2020 1.57678096672626