Year 1=low to 6=high 2005 3.62 2006 3.6 2007 3.7375000000000003 2008 3.7874999999999996 2009 3.7333333333333334 2010 3.755555555555555 2011 3.7375 2012 3.75 2013 3.7249999999999996 2014 3.5799999999999996 2015 3.6 2016 3.6 2017 3.6 2018 3.62 2019 3.66 2020 3.65 2021 3.625 2022 3.65 2023 3.675