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