Year	number
2003	11.979166666666666
2004	11.3
2005	11.12280701754386
2006	10.931034482758621
2007	10.482758620689655
2008	9.913793103448276
2009	9.448275862068966
2010	9.310344827586206
2011	8.94915254237288
2012	8.85
2013	8.651515151515152
2014	8.621212121212121
2015	8.469696969696969
2016	8.287878787878787
2017	8.151515151515152
2018	7.651515151515151
2019	7.53030303030303