Year	number
2005	34.93023255813954
2006	34.422222222222224
2007	33.51111111111111
2008	32.26086956521739
2009	31.829787234042552
2010	29.914893617021278
2011	27.148936170212767
2012	21.458333333333332
2013	20.387755102040817
2014	17.408163265306122
2015	15.938775510204081
2016	14.244897959183673
2017	13.16326530612245
2018	13.6
2019	12.68