Year	1=extremely inefficient to 7=extremely efficient
2007	4.36274509803922
2008	4.45071827490793
2009	4.5507807857
2010	4.6072760341
2011	4.4
2012	4.4
2013	4.5
2014	4.5
2015	4.63284173289011
2016	4.6
2017	4.9