Year	1=low to 6=high
2005	3.5
2006	3.4
2007	3.8
2008	3.8
2009	3.9
2010	3.9
2011	3.9
2012	3.9
2013	3.9
2014	3.9
2015	3.8
2016	3.8
2017	3.8
2018	3.8
2019	3.8
2020	3.8
2021	3.7
2022	3.7
2023	3.7