Year	1=low to 6=high
2005	2.8
2006	2.6
2007	2.6
2008	2.6
2009	2.5
2010	2.7
2011	2.7
2012	2.5
2013	2.4
2014	2.3
2015	2.2
2016	2.3
2017	2.3
2018	2.3
2019	2.3
2020	2.3
2021	2.3
2022	2.4
2023	2.5