Year	Number
2004-01-01	0
2005-01-01	0
2006-01-01	18
2007-01-01	30
2008-01-01	30
2009-01-01	27
2010-01-01	28
2011-01-01	27
2012-01-01	22
2013-01-01	11
2014-01-01	12
2015-01-01	11
2016-01-01	10
2017-01-01	12