Year	number
2004	7.357142857142857
2005	7.133333333333334
2006	7.0625
2007	7
2008	6.1875
2009	5.823529411764706
2010	5.823529411764706
2011	5.764705882352941
2012	5.764705882352941
2013	5.470588235294118
2014	5.352941176470588
2015	5.117647058823529
2016	5.0588235294117645
2017	5
2018	5
2019	5.117647058823529