Year	number
2003	10.418604651162791
2004	10.1875
2005	10.320754716981131
2006	10.185185185185185
2007	9.962962962962964
2008	9.37037037037037
2009	8.89090909090909
2010	8.709090909090909
2011	8.236363636363636
2012	8.192982456140351
2013	8.017241379310345
2014	7.741379310344827
2015	7.627118644067797
2016	7.372881355932203
2017	7.169491525423729
2018	7.0508474576271185
2019	6.864406779661017