Year	Number
2004-01-01	5734784
2005-01-01	7690162
2006-01-01	8918533
2007-01-01	9556036
2008-01-01	11801937
2009-01-01	13606654
2010-01-01	15114327
2011-01-01	17822224
2012-01-01	17747555
2013-01-01	17855386
2014-01-01	18052917
2015-01-01	17147115
2016-01-01	17108305