Year	1=extremely inefficient to 7=extremely efficient
2007	3.49674540872509
2008	3.53215127643738
2009	3.72613188380755
2010	3.86324798924464
2011	3.80175438596491
2012	3.76491228070175
2013	3.7593220338983
2014	3.7719298245614
2015	3.80076983949392
2016	3.79821428571429
2017	3.92641509433962