Year	1=extremely inefficient to 7=extremely efficient
2007	2.98550724637681
2008	3.10053177786893
2009	3.5728832681
2010	4.0274428541
2011	4.2
2012	3.7
2013	3.3
2014	3.4
2015	3.53411419791775
2016	3.5
2017	4