Year	Number
2004-01-01	520
2005-01-01	745
2006-01-01	1741
2007-01-01	1918
2008-01-01	2294
2009-01-01	2679
2010-01-01	4154
2011-01-01	4550
2012-01-01	4544
2013-01-01	4888
2014-01-01	17362
2015-01-01	20444
2016-01-01	21561