Year	1=low to 6=high
2006	2.3
2007	2.3
2008	2.5
2009	2.6
2010	2.6
2011	2.7
2012	2.7
2013	2.6
2014	2.6
2015	2.6
2016	2.6
2017	2.6
2018	2.6
2019	2.7
2020	2.7
2022	1.7
2023	1.7