Year	number
2003	11.758620689655173
2004	11.235294117647058
2005	11.18918918918919
2006	10.973684210526315
2007	10.710526315789474
2008	10.210526315789474
2009	9.68421052631579
2010	9.473684210526315
2011	8.868421052631579
2012	8.578947368421053
2013	8.394736842105264
2014	8.078947368421053
2015	8.025641025641026
2016	7.717948717948718
2017	7.358974358974359
2018	7.17948717948718
2019	7.128205128205129