Year Number 2004-01-01 4104 2005-01-01 4588 2006-01-01 6079 2007-01-01 7543 2008-01-01 8893 2009-01-01 9950 2010-01-01 10885 2011-01-01 11766 2012-01-01 12712 2013-01-01 13883 2014-01-01 15516 2015-01-01 17223 2016-01-01 17887