Year	1=extremely inefficient to 7=extremely efficient
2007	5.35897435897436
2008	5.45363705712582
2009	5.763852278
2010	5.6834493907
2011	5.5
2012	5.5
2013	5.4
2014	5.5
2015	5.58825263734591
2016	5.6
2017	5.5