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