Year	1=extremely inefficient to 7=extremely efficient
2007	3.29066056713042
2008	3.27494368886863
2009	3.62649187974615
2010	3.90142443342667
2011	3.86666666666667
2012	3.76060606060606
2013	3.59411764705882
2014	3.525
2015	3.58284750421927
2016	3.584375
2017	3.73548387096774