Year	Number
2004-01-01	12964
2005-01-01	21909
2006-01-01	34941
2007-01-01	87962
2008-01-01	397200
2009-01-01	428653
2010-01-01	453872
2011-01-01	481331
2012-01-01	492485
2013-01-01	509990
2014-01-01	531557
2015-01-01	551092
2016-01-01	548238