Year	1=extremely inefficient to 7=extremely efficient
2007	4.45454545454545
2008	4.56611497402597
2009	4.5917452627
2010	4.619650916
2011	4.6
2012	4.6
2013	4.6
2014	4.7
2015	4.74410915374756
2016	4.7
2017	4.6