Year	1=extremely inefficient to 7=extremely efficient
2007	4.34502923976608
2008	4.55609834611034
2009	4.6357602646
2010	4.4505364426
2011	4.4
2012	4.5
2013	4.6
2014	4.5
2015	4.46941326748241
2016	4.5
2017	4.8