Year	number
2003	10.223880597014926
2004	9.86111111111111
2005	9.846625766871165
2006	9.748502994011975
2007	9.411764705882353
2008	8.900584795321638
2009	8.488372093023257
2010	8.343023255813954
2011	7.982758620689655
2012	7.949438202247191
2013	7.818888888888889
2014	7.65984126984127
2015	7.47421052631579
2016	7.260263157894738
2017	7.068315789473684
2018	6.821465968586388
2019	6.603193717277487