Year	Number
2004-01-01	30
2005-01-01	32
2006-01-01	32
2007-01-01	23
2008-01-01	25
2009-01-01	28
2010-01-01	28
2011-01-01	31
2012-01-01	32
2013-01-01	41
2014-01-01	39
2015-01-01	40
2016-01-01	39
2017-01-01	39