Year	Number
2004-01-01	26
2005-01-01	27
2006-01-01	23
2007-01-01	21
2008-01-01	19
2009-01-01	18
2010-01-01	18
2011-01-01	18
2012-01-01	18
2013-01-01	18
2014-01-01	18
2015-01-01	17
2016-01-01	18
2017-01-01	18