Year	number
2003	11.617647058823529
2004	10.972222222222221
2005	10.613636363636363
2006	10.444444444444445
2007	9.88888888888889
2008	9.4
2009	8.869565217391305
2010	8.73913043478261
2011	8.478260869565217
2012	8.361702127659575
2013	8.185098039215687
2014	8.11
2015	7.96078431372549
2016	7.746078431372549
2017	7.648039215686275
2018	7.243921568627451
2019	7.239411764705883