Year	1=extremely inefficient to 7=extremely efficient
2007	5.21794871794872
2008	5.37458455946864
2009	5.464008
2010	5.3400066661
2011	5.2
2012	5.2
2013	5.3
2014	5.3
2015	5.26977236742354
2016	5.3
2017	5.5