Year	number
2005	32.63636363636363
2006	29.272727272727273
2007	28.181818181818183
2008	27.90909090909091
2009	27.90909090909091
2010	26.90909090909091
2011	26.545454545454547
2012	17
2013	14.727272727272727
2014	12.363636363636363
2015	10.272727272727273
2016	10.090909090909092
2017	10.090909090909092
2018	9.909090909090908
2019	9.909090909090908