Year 1=low to 6=high 2005 3.8 2006 3.7 2007 3.7 2008 3.7 2009 3.7 2010 3.7 2011 3.7 2012 3.7 2013 3.7 2014 3.7 2015 3.7 2016 3.7 2017 3.7 2018 3.7 2019 3.7 2020 3.7 2021 3.7 2022 3.7 2023 3.7