Year	Number
2004-01-01	17
2005-01-01	20
2006-01-01	22
2007-01-01	25
2008-01-01	26
2009-01-01	26
2010-01-01	27
2011-01-01	30
2012-01-01	38
2013-01-01	50
2014-01-01	58
2015-01-01	57
2016-01-01	57