Year	Number
2006-01-01	1
2007-01-01	6
2008-01-01	10
2009-01-01	11
2010-01-01	11
2011-01-01	12
2012-01-01	12
2013-01-01	12
2014-01-01	11
2015-01-01	8
2016-01-01	8
2017-01-01	7