Year	1=low to 6=high
2005	3.1
2006	3.1
2007	3
2008	3
2009	3.2
2010	3.3
2011	3.1
2012	3.1
2013	3
2014	3
2015	3
2016	3
2017	3
2018	3.1
2019	3.2
2020	3.4
2021	3.4
2022	3.4
2023	3.4