Year	Number
2004-01-01	5
2005-01-01	5
2006-01-01	10
2007-01-01	17
2008-01-01	20
2009-01-01	22
2010-01-01	22
2011-01-01	23
2012-01-01	20
2013-01-01	19
2014-01-01	19
2015-01-01	18
2016-01-01	16