Year	number
2003	12
2004	11.555555555555555
2005	11.526315789473685
2006	11.05
2007	10.35
2008	9.2
2009	8.047619047619047
2010	7.619047619047619
2011	7.190476190476191
2012	6.809523809523809
2013	6.181818181818182
2014	6.090909090909091
2015	5.7272727272727275
2016	5.590909090909091
2017	5.454545454545454
2018	5.136363636363637
2019	5.090909090909091