Year	1=extremely inefficient to 7=extremely efficient
2007	3.7037037037037
2008	3.85420054669775
2009	4.45500815
2010	4.6554863865
2011	4.4
2012	4.3
2013	4.4
2014	4.4
2015	4.27206317229237
2016	4.3
2017	4.4