Year	1=extremely inefficient to 7=extremely efficient
2007	3.33921805369651
2008	3.35200103199834
2009	3.59430226764483
2010	3.80574867087935
2011	3.734375
2012	3.69387755102041
2013	3.6578431372549
2014	3.63535353535353
2015	3.65405580588929
2016	3.65567010309278
2017	3.76559139784946