Year	Number
2004-01-01	19
2005-01-01	18
2006-01-01	16
2007-01-01	15
2008-01-01	15
2009-01-01	12
2010-01-01	9
2011-01-01	9
2012-01-01	7
2013-01-01	7
2014-01-01	7
2015-01-01	2
2016-01-01	2