| Year | Value | | 2020 | 0.87720150035199 | | 2019 | 0.87017484228735 | | 2018 | 0.87793945575171 | | 2017 | 0.89087251986285 | | 2016 | 0.91661911809059 | | 2015 | 0.92148944549018 | | 2014 | 0.93499768447826 | | 2013 | 0.95641784242436 | | 2012 | 0.97563408348877 | | 2011 | 0.98410965358327 | | 2010 | 1.0124053694246 | | 2009 | 1.0118346859772 | | 2008 | 1.0425507876959 | | 2007 | 1.058551319254 | | 2006 | 1.0698412194577 | | 2005 | 1.1449008578859 | | 2004 | 1.1104371528339 | | 2003 | 1.1520566760441 | | 2002 | 1.1707316630809 | | 2001 | 1.1826446408562 | | 2000 | 1.2316443907714 | | 1999 | 1.3084410215237 | | 1998 | 1.347664500418 | | 1997 | 1.360405552257 | | 1996 | 1.3933598667546 | | 1995 | 1.4367211285137 | | 1994 | 1.3741300393137 | | 1993 | 1.4147026026912 | | 1992 | 1.4684520285207 | | 1991 | 1.5685153378251 |
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