Year Number 2004-01-01 156 2005-01-01 209 2006-01-01 265 2007-01-01 353 2008-01-01 436 2009-01-01 412 2010-01-01 392 2011-01-01 433 2012-01-01 521 2013-01-01 555 2014-01-01 560 2015-01-01 550