Year	1=extremely inefficient to 7=extremely efficient
2007	4.09090909090909
2008	3.98451866748946
2009	4.0508158
2010	4.0835975385
2011	4
2012	3.8
2013	3.9
2014	4.2
2015	4.14406855427034
2016	4.1
2017	4.1