Year	1=low to 6=high
2005	3.6
2006	3.6
2007	3.6
2008	3.6
2009	3.6
2010	3.6
2011	3.7
2012	3.7
2013	3.7
2014	3.6
2015	3.6
2016	3.7
2017	3.7
2018	3.7
2019	3.6
2020	3.6
2021	3.6
2022	3.6
2023	3.5