Year	number
2004	8
2005	7.888888888888889
2006	7.888888888888889
2007	7.8
2008	7.8
2009	7.6
2010	7.6
2011	7.636363636363637
2012	7.545454545454546
2013	7.545454545454546
2014	7.454545454545454
2015	7.545454545454546
2016	7.090909090909091
2017	7
2018	7
2019	7