1997 12,348
1998 12,390
1999 12,100
2000 11,944
2001 12,347
2002 12,656
2003 13,306
2004 14,024
2005 14,545
2006 15,209
2007 15,806
2008 16,236
2009 16,500
2010 16,967
2011 17,577
2012 18,361
2013 18,915