Year Sterling 1997-12-31 10902 1998-12-31 13437 1999-12-31 14236 2000-12-31 15366 2001-12-31 17484 2002-12-31 20258 2003-12-31 22656 2004-12-31 24383 2005-12-31 28428 2006-12-31 33331 2007-12-31 36580 2008-12-31 33600 2009-12-31 35714 2010-12-31 35422 2011-12-31 31238 2012-12-31 32339 2013-12-31 35586 2014-12-31 39318 2015-12-31 43804 2016-12-31 46947 2017-12-31 52524 2018-12-31 56643 2019-12-31 56446