Year 1=low to 6=high 2005 3.4576719576719577 2006 3.4364102564102565 2007 3.456410256410256 2008 3.455384615384615 2009 3.4651741293532337 2010 3.45771144278607 2011 3.439613526570048 2012 3.3826291079812205 2013 3.3495370370370368 2014 3.3379627314814813 2015 3.303240648148148 2016 3.246479107981221 2017 3.2106481481481484 2018 3.2089201877934266 2019 3.2260274429223728 2020 3.2237442922374417 2021 3.2152778055555555 2022 3.157657702702702 2023 3.1509009324324313