Year	Number
2004-01-01	8
2005-01-01	8
2006-01-01	9
2007-01-01	10
2008-01-01	10
2009-01-01	10
2010-01-01	12
2011-01-01	12
2012-01-01	12
2013-01-01	15
2014-01-01	15
2015-01-01	15
2016-01-01	16