Year	1=extremely inefficient to 7=extremely efficient
2007	2.86904761904762
2008	2.76451205648604
2009	2.8070628892
2010	2.7383633741
2011	2.7
2012	2.3
2013	2.1
2014	2
2015	2.05562960147858
2016	2.1
2017	2.8