Year	1=low to 6=high
2005	3.7
2006	3.7
2007	3.6
2008	3.6
2009	3.6
2010	3.5
2011	3.7
2012	3.6
2013	3.6
2014	3.5
2015	3.4
2016	3.4
2017	3.4
2018	3.4
2019	3.4
2020	3.4
2021	3.4
2022	3.4
2023	3.4