Year 1=low to 6=high 2005 3.3024999999999998 2006 3.29390243902439 2007 3.3166666666666664 2008 3.309756097560976 2009 3.3260162601626027 2010 3.3254065040650413 2011 3.327380952380954 2012 3.332142857142859 2013 3.3180232558139524 2014 3.3302851219512184 2015 3.3168705691056926 2016 3.2896933333333345 2017 3.2837719298245616 2018 3.2695175438596484 2019 3.273931641025641 2020 3.2701754385964916 2021 3.255263078947369 2022 3.2435897179487188 2023 3.2472222564102564