Year	number
2003	12.461538461538462
2004	11.9375
2005	11.555555555555555
2006	11.555555555555555
2007	10.7
2008	9.8
2009	9.55
2010	9.65
2011	9.5
2012	9.380952380952381
2013	9.142857142857142
2014	8.952380952380953
2015	8.818181818181818
2016	8.590909090909092
2017	8.090909090909092
2018	7.454545454545454
2019	6.7727272727272725