Year	1=extremely inefficient to 7=extremely efficient
2007	4.78823529411765
2008	4.7203919579576
2009	4.7641093339
2010	4.94274135
2011	4.9
2012	4.6
2013	4.7
2014	4.7
2015	4.75982819607383
2016	4.8
2017	4.8