Year	1=extremely inefficient to 7=extremely efficient
2007	2.24545454545455
2008	2.37522624450758
2009	3.1057092449
2010	3.5013051787
2011	3.5
2012	3.6
2013	3.9
2015	3.85964918136597
2016	3.9
2017	3.5