Year	1=low to 6=high
2005	4.3
2006	4.3
2007	4
2008	4
2009	3.9
2010	3.7
2011	3.7
2012	3.5
2013	3.5
2014	3.4
2015	3.4
2016	3.3
2017	3.4
2018	3.4
2019	3.4
2020	3.4
2021	3.4
2022	3.4
2023	3.4