Year	Number
2004-01-01	17
2005-01-01	19
2006-01-01	21
2007-01-01	21
2008-01-01	25
2009-01-01	25
2010-01-01	25
2011-01-01	25
2012-01-01	25
2013-01-01	25
2014-01-01	25
2015-01-01	26
2016-01-01	26