Year	1=extremely inefficient to 7=extremely efficient
2007	6.07142857142857
2008	5.94348792169312
2009	6.1479982
2010	6.4695307889
2011	6.2
2012	6.1
2013	6.1
2014	6.1
2015	6.21223414026458
2016	6.2
2017	6