Year	Number
2004-01-01	3
2005-01-01	4
2006-01-01	7
2007-01-01	7
2008-01-01	9
2009-01-01	13
2010-01-01	13
2011-01-01	13
2012-01-01	14
2013-01-01	14
2014-01-01	13
2015-01-01	11
2016-01-01	13
2017-01-01	13