Year	number
2005	15.38888888888889
2006	15.567567567567568
2007	15.567567567567568
2008	14.486486486486486
2009	14.621621621621621
2010	14.783783783783784
2011	14.675675675675675
2012	14.64864864864865
2013	15.108108108108109
2014	15.27027027027027
2015	15.378378378378379
2016	15.513513513513514
2017	15.405405405405405
2018	15.405405405405405
2019	15.45945945945946