Year	Number
2004-01-01	13
2005-01-01	16
2006-01-01	15
2007-01-01	16
2008-01-01	16
2009-01-01	16
2010-01-01	16
2011-01-01	23
2012-01-01	23
2013-01-01	23
2014-01-01	23
2015-01-01	24
2016-01-01	24