Year	1=extremely inefficient to 7=extremely efficient
2007	4.79350287656079
2008	4.75665964432099
2009	4.8077359271
2010	4.86188649871765
2011	4.79705882352941
2012	4.80882352941176
2013	4.88235294117647
2014	4.94242424242424
2015	4.89598907500108
2016	4.9
2017	5.01818181818182