Year	1=extremely inefficient to 7=extremely efficient
2007	4.13978494623656
2008	4.34437194963214
2009	4.246320713
2010	4.2140951529
2011	4.2
2012	3.9
2013	3.9
2014	3.7
2015	3.48100296671286
2016	3.5
2017	3.2