Year	1=extremely inefficient to 7=extremely efficient
2007	3.83444270661306
2008	3.89682267863519
2009	4.07194156841463
2010	4.17653078541628
2011	4.13720930232558
2012	4.11627906976744
2013	4.14090909090909
2014	4.16511627906977
2015	4.13419076967664
2016	4.13095238095238
2017	4.24146341463415