Year	1=extremely inefficient to 7=extremely efficient
2007	5.24590163934426
2008	4.99185313727097
2009	5.093564665
2010	5.1331298013
2011	4.7
2012	4.9
2013	4.9
2014	4.7
2015	4.70156070455428
2016	4.7
2017	5.3