Year	Number
2004-01-01	18688945
2005-01-01	18789821
2006-01-01	18577836
2007-01-01	18561377
2008-01-01	18371883
2009-01-01	19441071
2010-01-01	19556257
2011-01-01	20174092
2012-01-01	20298084
2013-01-01	22152719
2014-01-01	22677900
2015-01-01	21010838
2016-01-01	18470920