Year	1=extremely inefficient to 7=extremely efficient
2007	4.23913043478261
2008	4.2396500679089
2009	4.1115411152
2010	4.141357665
2011	4.1
2012	4.1
2013	4.3
2014	4.5
2015	4.56538427992712
2016	4.6
2017	4.3