Year	1=low to 6=high
2005	3.4
2006	3.4
2007	3.5
2008	3.6
2009	3.3
2010	3
2011	2.8
2012	2.6
2013	2.5
2014	2.6
2015	2.7
2016	2.8
2017	2.8
2018	2.8
2019	2.7
2020	2.7
2021	2.7
2022	2.7
2023	2.7