Year	1=extremely inefficient to 7=extremely efficient
2007	5.36666666666667
2008	5.41967096135266
2009	5.23986745
2010	5.2279451957
2011	5.2
2012	5.1
2013	5.3
2014	5.3
2015	5.14726633692897
2016	5.1
2017	5