Year	Number
2004-01-01	4
2005-01-01	4
2006-01-01	4
2007-01-01	4
2008-01-01	5
2009-01-01	5
2010-01-01	7
2011-01-01	7
2012-01-01	9
2013-01-01	9
2014-01-01	9
2015-01-01	10
2016-01-01	10