Year	1=low to 6=high
2005	2.4
2006	2.3
2007	2.3
2008	2.3
2009	2.2
2010	2.2
2011	2.2
2012	2.2
2013	2.2
2014	2.2
2015	2.2
2016	2.2
2017	2.2
2018	2.1
2019	2.1
2020	2.1
2021	1.9
2022	1.8
2023	1.8