Year	1=extremely inefficient to 7=extremely efficient
2007	3.15561966733553
2008	3.08279030085416
2009	3.48474493936316
2010	3.83563928105789
2011	3.765
2012	3.69545454545454
2013	3.46086956521739
2014	3.36666666666667
2015	3.43438702714687
2016	3.44
2017	3.595