Year Sterling 1997-12-31 6592 1998-12-31 6789 1999-12-31 6123 2000-12-31 6383 2001-12-31 6855 2002-12-31 6228 2003-12-31 6245 2004-12-31 7801 2005-12-31 9754 2006-12-31 9280 2007-12-31 10427 2008-12-31 9349 2009-12-31 11735 2010-12-31 11636 2011-12-31 8749 2012-12-31 11214 2013-12-31 11867 2014-12-31 12189 2015-12-31 14795 2016-12-31 15545 2017-12-31 17011 2018-12-31 18064 2019-12-31 17762 2020-12-31 21458 2021-12-31 20335 2022-12-31 18669 2023-12-31 19771