Year	Number
2004-01-01	18841
2005-01-01	29225
2006-01-01	44708
2007-01-01	107815
2008-01-01	430258
2009-01-01	462039
2010-01-01	486570
2011-01-01	501799
2012-01-01	514521
2013-01-01	538606
2014-01-01	561987
2015-01-01	582680
2016-01-01	577038