Year	1=low to 6=high
2005	2.7
2006	2.7
2007	2.7
2008	2.5
2009	2.6
2010	2.6
2011	2.7
2012	2.8
2013	2.8
2014	2.8
2015	2.9
2016	2.9
2017	2.8
2018	2.8
2019	2.7
2020	2.8
2021	2.9
2022	2.9
2023	2.9