Year	number
2005	15.161290322580646
2006	14.838709677419354
2007	14.870967741935484
2008	14.35483870967742
2009	14.625
2010	14.375
2011	14.4375
2012	14.705882352941176
2013	14.531764705882352
2014	14.678823529411764
2015	14.678823529411764
2016	14.82060606060606
2017	14.797272727272727
2018	14.706363636363637
2019	14.706363636363637