Year	Number
2004-01-01	23
2005-01-01	24
2006-01-01	23
2007-01-01	23
2008-01-01	28
2009-01-01	28
2010-01-01	28
2011-01-01	28
2012-01-01	30
2013-01-01	32
2014-01-01	37
2015-01-01	37