Year	Number
2004-01-01	16
2005-01-01	17
2006-01-01	18
2007-01-01	18
2008-01-01	19
2009-01-01	20
2010-01-01	21
2011-01-01	23
2012-01-01	24
2013-01-01	25
2014-01-01	25
2015-01-01	26
2016-01-01	27