Year	1=extremely inefficient to 7=extremely efficient
2007	5.25531914893617
2008	5.12628850917655
2009	5.312462107
2010	5.346258349
2011	5.5
2012	5.3
2013	4.9
2014	4.7
2015	4.9181731134358
2016	4.9
2017	5.2