Year	1=low to 6=high
2005	3.3
2006	3.4
2007	3.4
2008	3.5
2009	3.5
2010	3.4
2011	3.3
2012	3.3
2013	3.3
2014	3.3
2015	3.2
2016	3.1
2017	3.1
2018	3.2
2019	3.2
2020	3.2
2021	3.2
2022	3.2
2023	3.3