Year 1=low to 6=high 2005 3.5 2006 4 2007 4 2008 4 2009 3.5 2010 3.5 2011 3.5 2012 3.5 2013 3.5 2014 4 2015 4 2016 4 2017 4 2018 4 2019 3.5 2020 4 2021 4 2022 4 2023 4