Year | Value | 2021 | 16.780410676456 | 2020 | 16.442596894579 | 2019 | 16.677622662804 | 2018 | 16.587065472935 | 2017 | 15.184856960841 | 2016 | 13.353181426945 | 2015 | 14.393963933014 | 2014 | 15.761030331691 | 2013 | 14.347109316664 | 2012 | 14.892364297402 | 2011 | 14.715943318396 | 2010 | 12.834842405292 | 2009 | 11.687515825699 | 2008 | 13.259303782646 | 2007 | 14.082514581153 | 2006 | 13.711529295592 | 2005 | 14.794768597768 | 2004 | 15.317058633854 | 2003 | 14.859519879141 | 2002 | 15.440012868459 | 2001 | 16.540704458815 | 1999 | 16.954308489197 | 1998 | 16.188187128885 | 1997 | 16.05009567388 | 1996 | 16.105617954565 | 1995 | 15.689500158176 | 1994 | 17.236518286106 | 1993 | 15.040171116806 | 1992 | 18.710926252361 | 1991 | 17.493831198878 | 1990 | 19.482883359802 |
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