Year	number
2003	11.303370786516854
2004	10.896907216494846
2005	10.803571428571429
2006	10.666666666666666
2007	10.298245614035087
2008	9.780701754385966
2009	9.295652173913043
2010	9.104347826086956
2011	8.730434782608695
2012	8.669491525423728
2013	8.566428571428572
2014	8.40484126984127
2015	8.24724409448819
2016	8.011417322834648
2017	7.810866141732284
2018	7.455905511811024
2019	7.269370078740159