Year	1=extremely inefficient to 7=extremely efficient
2007	3.31760880476843
2008	3.35255078815899
2009	3.59897998549394
2010	3.76752441758857
2011	3.71388888888889
2012	3.6830985915493
2013	3.66315789473684
2014	3.63783783783784
2015	3.65751702756777
2016	3.65694444444445
2017	3.7530303030303