Year	Number
2004-01-01	6
2005-01-01	8
2006-01-01	9
2007-01-01	10
2008-01-01	11
2009-01-01	11
2010-01-01	10
2011-01-01	11
2012-01-01	13
2013-01-01	16
2014-01-01	16
2015-01-01	17
2016-01-01	18
2017-01-01	19