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