Year	Number
2004-01-01	8887808
2005-01-01	11889479
2006-01-01	14645199
2007-01-01	16006845
2008-01-01	16783790
2009-01-01	17506648
2010-01-01	18789465
2011-01-01	19125812
2012-01-01	19238137
2013-01-01	19375784
2014-01-01	19507669
2015-01-01	19835113
2016-01-01	20189236