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	9.100909090909092
2014	8.891363636363637
2015	8.772727272727273
2016	8.492272727272727
2017	8.401363636363635
2018	8.156363636363636
2019	8.156363636363636