Year	1=low to 6=high
2005	2.3
2006	2.3
2007	2.3
2008	2.2
2009	2.2
2010	2.2
2011	2.2
2012	2.2
2013	2.4
2014	2.5
2015	2.5
2016	2.5
2017	2.5
2018	2.5
2019	2.5
2020	2.5
2021	2.5
2022	2.5
2023	2.6