Year	1=extremely inefficient to 7=extremely efficient
2007	3.63013698630137
2008	3.95991874755382
2009	4.4306564953
2010	4.7109626626
2011	4.7
2012	4.4
2013	4.2
2014	4.2
2015	4.17295822816737
2016	4.2
2017	4.4