Year	Number
2004-01-01	38
2005-01-01	32
2006-01-01	33
2007-01-01	33
2008-01-01	28
2009-01-01	24
2010-01-01	24
2011-01-01	20
2012-01-01	18
2013-01-01	16
2014-01-01	15
2015-01-01	15
2016-01-01	16
2017-01-01	16