Year	1=extremely inefficient to 7=extremely efficient
2007	4.01123595505618
2008	3.87568983474503
2009	3.9929696056
2010	4.1811728197
2011	4
2012	4.1
2013	4.1
2014	4
2015	4.01463694920701
2016	4
2017	4.3