Year	1=extremely inefficient to 7=extremely efficient
2007	3.39470980020884
2008	3.40138650943807
2009	3.6367168892875
2010	3.86220829586087
2011	3.71923076923077
2012	3.668
2013	3.684
2014	3.64583333333333
2015	3.46976232576831
2016	3.47272727272727
2017	3.52