Year	Number
2004-01-01	17
2005-01-01	19
2006-01-01	20
2007-01-01	20
2008-01-01	20
2009-01-01	20
2010-01-01	11
2011-01-01	10
2012-01-01	10
2013-01-01	9
2014-01-01	10
2015-01-01	11
2016-01-01	12