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