Year 1=low to 6=high 2005 3.189189189189189 2006 3.2162162162162162 2007 3.2162162162162162 2008 3.1621621621621623 2009 3.210526315789474 2010 3.3026315789473686 2011 3.3289473684210527 2012 3.282051282051282 2013 3.282051282051282 2014 3.276315789473684 2015 3.276315789473684 2016 3.25 2017 3.2435897435897436 2018 3.3289473684210527 2019 3.3205128205128207 2020 3.3461538461538463 2021 3.371794871794872 2022 3.4358974358974357 2023 3.41025641025641