Year Number 2005-01-01 18434 2006-01-01 23587 2007-01-01 22805 2008-01-01 21026 2009-01-01 18226 2010-01-01 18895 2011-01-01 17727 2012-01-01 15800 2013-01-01 15110 2014-01-01 14525 2015-01-01 15602 2016-01-01 16163 2017-01-01 17320