Year	number
2003	9.609756097560975
2004	9.142857142857142
2005	9.162790697674419
2006	8.777777777777779
2007	8.422222222222222
2008	7.586956521739131
2009	7.042553191489362
2010	6.808510638297872
2011	6.48936170212766
2012	6.416666666666667
2013	5.987755102040816
2014	5.7693877551020405
2015	5.504081632653061
2016	5.408163265306122
2017	5.326530612244898
2018	5.34
2019	5.26