Year	Number
2004-01-01	27
2005-01-01	27
2006-01-01	28
2007-01-01	30
2008-01-01	30
2009-01-01	26
2010-01-01	27
2011-01-01	26
2012-01-01	25
2013-01-01	22
2014-01-01	22
2015-01-01	23
2016-01-01	22
2017-01-01	21