Year	1=extremely inefficient to 7=extremely efficient
2007	3.88277018736156
2008	3.87798450476141
2009	4.05542422872782
2010	4.19846333153044
2011	4.12394366197183
2012	4.0875
2013	4.06756756756757
2014	4.06041666666667
2015	4.06439931187293
2016	4.06714285714286
2017	4.18978102189781