Year	number
2003	10.372093023255815
2004	10.104166666666666
2005	10.226415094339623
2006	10.092592592592593
2007	9.87037037037037
2008	9.277777777777779
2009	8.8
2010	8.636363636363637
2011	8.163636363636364
2012	8.12280701754386
2013	7.948275862068965
2014	7.672413793103448
2015	7.559322033898305
2016	7.305084745762712
2017	7.101694915254237
2018	6.983050847457627
2019	6.796610169491525