Year	number
2003	10.5
2004	10.317073170731707
2005	10.456521739130435
2006	10.456521739130435
2007	10.217391304347826
2008	9.826086956521738
2009	9.58695652173913
2010	9.369565217391305
2011	9.021739130434783
2012	8.957446808510639
2013	8.901960784313726
2014	8.72549019607843
2015	8.490196078431373
2016	8.313725490196079
2017	8.098039215686274
2018	7.686274509803922
2019	7.2745098039215685