Year	1=extremely inefficient to 7=extremely efficient
2007	4.275
2008	4.50024357777778
2009	4.8029018156
2010	4.786682046
2011	4.5
2012	4.5
2013	4.6
2014	4.6
2015	4.49395172451482
2016	4.5
2017	4.6