Year	1=low to 6=high
2005	2.8
2006	2.8
2007	2.8
2008	2.8
2009	2.8
2010	2.8
2011	2.8
2012	2.6
2013	2.7
2014	2.7
2015	2.7
2016	2.7
2017	2.7
2018	3
2019	3.1
2020	3.2
2021	3.1
2022	3.1
2023	3.1