Year | Value | 2019 | 6.2641042574239 | 2016 | 7.4711577727349 | 2015 | 9.6749865850339 | 2014 | 7.6932083089393 | 2013 | 8.6692290897356 | 2012 | 8.0920947987611 | 2011 | 7.6605990627204 | 2010 | 6.6995181584529 | 2009 | 7.8378027287406 | 2008 | 6.7480209257048 | 2007 | 8.4259111987091 | 2006 | 9.2092498170172 | 2005 | 10.421574463606 | 2004 | 11.011625514814 | 2003 | 11.601425855529 | 2002 | 12.462485924466 | 2001 | 12.768740110519 | 1999 | 14.018549930843 | 1998 | 14.276683716892 | 1997 | 15.096894543463 | 1996 | 15.307603989283 | 1995 | 15.724940268126 | 1994 | 16.228987275291 | 1993 | 17.203692899888 | 1992 | 16.577897268525 | 1991 | 15.726108044129 |
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