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 4 2013 4.5 2014 4.5 2015 4.5 2016 4.5 2017 4.5 2018 4.5 2019 4.5