Year	number
2003	12.352941176470589
2004	11.85
2005	11.818181818181818
2006	11.434782608695652
2007	11.173913043478262
2008	10.347826086956522
2009	9.478260869565217
2010	9.217391304347826
2011	8.565217391304348
2012	8.625
2013	8.541666666666666
2014	8.25
2015	8.24
2016	7.84
2017	7.44
2018	7.32
2019	7.24