Year	1=extremely inefficient to 7=extremely efficient
2007	3.06989709187347
2008	3.07117859213748
2009	3.38880316009706
2010	3.71630528675556
2011	3.63589743589744
2012	3.59512195121951
2013	3.51860465116279
2014	3.45
2015	3.45366590633175
2016	3.4609756097561
2017	3.5525