Year	1=extremely inefficient to 7=extremely efficient
2007	5.49532710280374
2008	5.37950277386242
2009	5.3053440094
2010	5.2543006856
2011	5
2012	5.1
2013	5.2
2014	5.2
2015	5.08408188986224
2016	5.1
2017	5.3