Year	Number
2004-01-01	17
2005-01-01	17
2006-01-01	15
2007-01-01	15
2008-01-01	15
2009-01-01	14
2010-01-01	14
2011-01-01	12
2012-01-01	11
2013-01-01	11
2014-01-01	9
2015-01-01	8
2016-01-01	8