Year	Number
2004-01-01	18197184
2005-01-01	21360374
2006-01-01	22296248
2007-01-01	24036603
2008-01-01	28732961
2009-01-01	32178542
2010-01-01	33829981
2011-01-01	37419521
2012-01-01	38922826
2013-01-01	38374247
2014-01-01	39838146
2015-01-01	40628205
2016-01-01	41410345