Year	1=extremely inefficient to 7=extremely efficient
2007	4.72542865168464
2008	4.71465111880515
2009	4.77378696358571
2010	4.79490685643571
2011	4.70714285714286
2012	4.68571428571429
2013	4.76785714285714
2014	4.84285714285714
2015	4.80677303623633
2016	4.81428571428571
2017	4.94285714285714