Year	1=extremely inefficient to 7=extremely efficient
2007	2.9625
2008	2.75382817252747
2009	2.8193366358
2010	3.02742885
2011	2.8
2012	3
2013	3.2
2014	3.4
2015	3.53471179285435
2016	3.5
2017	3.6