Year 1=low to 6=high 2005 3.1556306306306303 2006 3.153378378378379 2007 3.1772522522522526 2008 3.1621621621621627 2009 3.1767543859649123 2010 3.1809210526315788 2011 3.204605263157895 2012 3.173931623931624 2013 3.170940170940171 2014 3.186404561403509 2015 3.172149824561403 2016 3.136842105263158 2017 3.1017094017094022 2018 3.1285087719298255 2019 3.100000000000001 2020 3.1091880341880356 2021 3.115598307692307 2022 3.127991487179488 2023 3.1397436410256407