Year	1=extremely inefficient to 7=extremely efficient
2007	3.37647058823529
2008	3.3109775605042
2009	3.5478318857
2010	3.5579659538
2011	3.4
2012	3.9
2013	4.3
2015	3.33333325386047
2016	3.3
2017	3.3