Year 1=low to 6=high 2005 3.2252252252252247 2006 3.2351351351351347 2007 3.2477477477477477 2008 3.2135135135135138 2009 3.2368421052631584 2010 3.210526315789474 2011 3.214912280701755 2012 3.1923076923076925 2013 3.2136752136752142 2014 3.2236845614035086 2015 3.2149125438596493 2016 3.1666666666666674 2017 3.1367521367521367 2018 3.1622807017543857 2019 3.106837606837606 2020 3.1153846153846145 2021 3.128205128205128 2022 3.153846128205128 2023 3.1709401538461535