Year	Number
2004-01-01	16
2005-01-01	16
2006-01-01	18
2007-01-01	21
2008-01-01	27
2009-01-01	27
2010-01-01	30
2011-01-01	36
2012-01-01	36
2013-01-01	36
2014-01-01	36