Year	1=extremely inefficient to 7=extremely efficient
2007	3.76229012750137
2008	3.92885176425239
2009	4.20406502653158
2010	4.3925998127421
2011	4.22272727272727
2012	4.16521739130435
2013	4.16666666666667
2014	4.12173913043478
2015	4.19015251364559
2016	4.185
2017	4.36842105263158