Year Number 1997 148000 1998 241000 1999 327000 2000 153000 2001 152000 2002 184000 2003 189000 2004 231000 2005 189000 2006 254000 2007 272000 2008 337000 2009 311000 2010 324000 2011 367000 2012 469000 2013 471000 2014 511000 2015 523000 2016 568000