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