Year	Number
2004-01-01	0
2005-01-01	0
2006-01-01	0
2007-01-01	0
2008-01-01	6
2009-01-01	12
2010-01-01	13
2011-01-01	17
2012-01-01	19
2013-01-01	22
2014-01-01	22
2015-01-01	28
2016-01-01	28