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