Year	number
2003	8.113636363636363
2004	7.8478260869565215
2005	7.88
2006	7.884615384615385
2007	7.6909090909090905
2008	7.232142857142857
2009	6.946428571428571
2010	6.875
2011	6.586206896551724
2012	6.593220338983051
2013	6.377419354838709
2014	6.20483870967742
2015	5.946774193548387
2016	5.774193548387097
2017	5.580645161290323
2018	5.555555555555555
2019	5.26984126984127