Year	1=extremely inefficient to 7=extremely efficient
2007	4.29613110767699
2008	4.3036137620002
2009	4.41476222402353
2010	4.5601471261125
2011	4.47058823529412
2012	4.50588235294118
2013	4.41052631578947
2014	4.42222222222222
2015	4.47569330152412
2016	4.48823529411765
2017	4.51764705882353