Year	number
2004	5.369565217391305
2005	5.4
2006	5.4423076923076925
2007	5.454545454545454
2008	5.464285714285714
2009	5.446428571428571
2010	5.303571428571429
2011	5.344827586206897
2012	5.389830508474576
2013	5.34516129032258
2014	5.312903225806451
2015	5.280645161290322
2016	5.280645161290322
2017	5.248387096774193
2018	5.307936507936508
2019	5.196825396825396