Year Sterling 1997-12-31 20728 1998-12-31 23259 1999-12-31 23594 2000-12-31 24188 2001-12-31 23361 2002-12-31 26939 2003-12-31 27269 2004-12-31 27048 2005-12-31 31624 2006-12-31 32217 2007-12-31 37202 2008-12-31 38730 2009-12-31 33900 2010-12-31 32543 2011-12-31 30975 2012-12-31 29124 2013-12-31 28961 2014-12-31 34258 2015-12-31 33151 2016-12-31 35555 2017-12-31 38167 2018-12-31 40434 2019-12-31 39099