Year Number 2004-01-01 397 2005-01-01 405 2006-01-01 407 2007-01-01 416 2008-01-01 430 2009-01-01 438 2010-01-01 441 2011-01-01 454 2012-01-01 443 2013-01-01 442 2014-01-01 488 2015-01-01 516 2016-01-01 539 2017-01-01 578