Year	Number
2004-01-01	14
2005-01-01	14
2006-01-01	17
2007-01-01	20
2008-01-01	30
2009-01-01	30
2010-01-01	30
2011-01-01	30
2012-01-01	30
2013-01-01	28
2014-01-01	28
2015-01-01	27
2016-01-01	27
2017-01-01	27