Year	1=extremely inefficient to 7=extremely efficient
2007	3.39864902046887
2008	3.43483756701441
2009	3.62416263323684
2010	3.81707679016585
2011	3.72727272727273
2012	3.67272727272727
2013	3.67173913043478
2014	3.61521739130435
2015	3.63106105246493
2016	3.63636363636364
2017	3.7452380952381