Year 1=low to 6=high 2005 1.5 2006 1.5 2007 1.5 2008 1.5 2009 2 2010 2 2011 2.5 2012 2.5 2013 2.5 2014 2.5 2015 3 2016 3 2017 3 2018 3.5 2019 3.5 2020 3.5 2021 4 2022 4 2023 4