Year Number 1985 13700 1989 20000 1990 20000 1991 20000 1992 24000 1993 24000 1994 22000 1995 29200 1996 29200 1997 29200 1998 29200 1999 29200 2000 27200 2001 29400 2002 29400 2003 29100 2004 29000 2005 29000 2007 29000 2008 29000 2009 29120 2010 29120 2011 29100 2012 29100 2013 29100 2014 29100 2015 29100 2016 29100 2017 29000 2018 29100 2019 29000 2020 24000