Year	1=extremely inefficient to 7=extremely efficient
2007	3.51456310679612
2008	3.68718270763579
2009	4.0307909435
2010	4.2799864882
2011	4.2
2012	4.4
2013	4.6
2014	4.7
2015	4.61614869855485
2016	4.6