Year	1=extremely inefficient to 7=extremely efficient
2007	4.30769230769231
2008	4.29485897861869
2009	4.2616200909
2010	4.3161926644
2011	4.5
2012	4.7
2013	4.8
2014	4.8
2015	4.66866318950914
2016	4.7
2017	5