Year 1=low to 6=high 2005 3.276719576719576 2006 3.2525641025641034 2007 3.2706410256410243 2008 3.266153846153846 2009 3.2768656716417905 2010 3.281592039800995 2011 3.2768115942028984 2012 3.243779342723005 2013 3.22962962962963 2014 3.231829629629631 2015 3.2119218055555563 2016 3.186971971830985 2017 3.1569444444444446 2018 3.1679577464788733 2019 3.160502273972603 2020 3.1599315068493157 2021 3.1624999722222227 2022 3.141891891891892 2023 3.142117135135135