Year % 2008 3.92151508288564 2009 5.93611112398252 2010 5.79213600421705 2011 4.68085453063316 2012 4.04289177410579 2013 3.64128702921644 2014 3.24484679094119 2015 3.12168564309893 2016 2.85780789685004 2017 2.84200004498428 2018 3.72802083553832 2019 3.89239038176021 2020 5.18028329482246 2021 4.45425562129511