Year	number
2003	10.328358208955224
2004	9.993055555555555
2005	9.969325153374234
2006	9.874251497005988
2007	9.547058823529412
2008	9.04093567251462
2009	8.627906976744185
2010	8.482558139534884
2011	8.120689655172415
2012	8.084269662921349
2013	7.9458730158730155
2014	7.786825396825397
2015	7.600526315789474
2016	7.386578947368421
2017	7.189368421052632
2018	6.9366492146596865
2019	6.713141361256545