Year 1=low to 6=high 2005 3.2514999999999996 2006 3.2334967320261443 2007 3.251307189542482 2008 3.2509803921568623 2009 3.253930817610063 2010 3.2555031446540883 2011 3.2480303030303044 2012 3.208040935672516 2013 3.192959770114943 2014 3.195259712643679 2015 3.1751442528735643 2016 3.1514622807017547 2017 3.1214080459770117 2018 3.1352339181286553 2019 3.1141242994350287 2020 3.107327586206898 2021 3.104970754385965 2022 3.0795197966101697 2023 3.0752825084745763