Year	1=low to 6=high
2005	3.6
2006	3.6
2007	3.8
2008	3.8
2009	3.8
2010	3.9
2011	3.8
2012	3.8
2013	3.8
2014	3.8
2015	3.8
2016	3.7
2017	3.7
2018	3.7
2019	3.7
2020	3.7
2021	3.7
2022	3.7
2023	3.7