Year	1=extremely inefficient to 7=extremely efficient
2007	2.48192771084337
2008	2.77949503712146
2009	3.1095929325
2010	3.3744677221
2011	3.4
2012	3.5
2013	3.3
2014	3.2
2015	3.31368096580718
2016	3.3
2017	3.4