Year	1=extremely inefficient to 7=extremely efficient
2007	2
2008	1.94105186046512
2009	2.3207554841
2010	2.696615418
2011	2.8
2012	2.8
2013	2.2
2014	2.1
2015	2.37971461877128
2016	2.4
2017	2.4