Year 1=low to 6=high 2005 3.3492063492063497 2006 3.3389743589743595 2007 3.3615384615384616 2008 3.3353846153846147 2009 3.3482587064676608 2010 3.328358208955224 2011 3.314009661835748 2012 3.284037558685447 2013 3.287037037037038 2014 3.289351898148147 2015 3.252314629629629 2016 3.2323941314553983 2017 3.1990740740740753 2018 3.1995305164319254 2019 3.166666652968036 2020 3.15296803652968 2021 3.166666680555555 2022 3.166666662162162 2023 3.175675675675676