Year	Number
2004-01-01	15
2005-01-01	16
2006-01-01	15
2007-01-01	15
2008-01-01	16
2009-01-01	22
2010-01-01	25
2011-01-01	27
2012-01-01	31
2013-01-01	31
2014-01-01	32
2015-01-01	31
2016-01-01	32