Year	1=extremely inefficient to 7=extremely efficient
2007	5.45631067961165
2008	5.63183862529846
2009	5.8172219978
2010	5.688757987
2011	5.5
2012	5
2013	4.9
2014	5
2015	4.89512331198293
2016	4.9
2017	5