Year	1=extremely inefficient to 7=extremely efficient
2007	3.48936170212766
2008	3.7955867834109
2009	3.86654425
2010	3.5206228443
2011	3.5
2012	3.4
2013	3.3
2014	3.2
2015	3.20245570720079
2016	3.2
2017	4.4