Year	1=extremely inefficient to 7=extremely efficient
2007	3.05195964787832
2008	3.0929484198285
2009	3.478282779825
2010	3.86768321109524
2011	3.70833333333333
2012	3.63461538461538
2013	3.50666666666667
2014	3.41428571428571
2015	3.45910420287041
2016	3.46923076923077
2017	3.58888888888889