Year	Number
2004-01-01	5734529
2005-01-01	7689907
2006-01-01	8918278
2007-01-01	9555781
2008-01-01	11801682
2009-01-01	13606393
2010-01-01	15114084
2011-01-01	17821984
2012-01-01	17747371
2013-01-01	17855257
2014-01-01	18052760
2015-01-01	17146974
2016-01-01	17108077