Year	1=extremely inefficient to 7=extremely efficient
2007	3.34424566650637
2008	3.33999328010381
2009	3.57732305837727
2010	3.80218968121905
2011	3.64583333333333
2012	3.58695652173913
2013	3.60434782608696
2014	3.56363636363636
2015	3.46976232576831
2016	3.47272727272727
2017	3.52