Year Age 1990 14000 1991 14000 1992 15000 1993 15000 1994 16000 1995 16000 1996 17000 1997 18000 1998 20000 1999 21000 2000 21000 2001 21000 2002 21000 2003 21000 2004 21000 2005 20000 2006 16000 2007 12000 2008 9600 2009 8500 2010 7300 2011 6400