Year	number
2003	13
2004	12.214285714285714
2005	10.85
2006	10.7
2007	10.1
2008	9.95
2009	9.7
2010	9.65
2011	9.55
2012	9.55
2013	9.090909090909092
2014	8.909090909090908
2015	8.772727272727273
2016	8.5
2017	8.409090909090908
2018	8.181818181818182
2019	8.181818181818182