Year	1=low to 6=high
2005	2.9
2006	2.9
2007	2.9
2008	2.9
2009	2.8
2010	2.8
2011	2.8
2012	2.8
2013	2.8
2014	2.9
2015	3
2016	3
2017	3
2018	3.1
2019	3.1
2020	3.2
2021	3.2
2022	3.2
2023	3.1