Year	1=low to 6=high
2005	3.4
2006	3.3
2007	3.3
2008	3.3
2009	3.3
2010	3.3
2011	3.3
2012	3.3
2013	3.3
2014	3.3
2015	3.3
2016	3.3
2017	3.3
2018	3.3
2019	3.4
2020	3.4
2021	3.5
2022	3.6
2023	3.7