Year	1=extremely inefficient to 7=extremely efficient
2007	4.52307692307692
2008	4.58814018972603
2009	5.1015904913
2010	5.3811002207
2011	5.2
2012	4.9
2013	4.7
2014	4.6
2015	4.47040783193978
2016	4.5
2017	4.7