Year	1=extremely inefficient to 7=extremely efficient
2007	3.05882352941176
2008	2.74699657962097
2009	3.4115410947
2010	4.1519533443
2011	3.7
2012	3.1
2013	3
2015	3.29230761528015
2016	3.3
2017	3.5