| Year | Value | | 2020 | 0.84264640771925 | | 2019 | 0.84126809527939 | | 2018 | 0.8437378310608 | | 2017 | 0.85588024902267 | | 2016 | 0.87780529473464 | | 2015 | 0.8832300249856 | | 2014 | 0.88785817734793 | | 2013 | 0.89384668489239 | | 2012 | 0.93183889527016 | | 2011 | 0.94811626478496 | | 2010 | 0.98195963257108 | | 2009 | 0.9781762094336 | | 2008 | 1.0061828146877 | | 2007 | 1.0164933129059 | | 2006 | 1.0250415319434 | | 2005 | 1.1094200648312 | | 2004 | 1.0732630379886 | | 2003 | 1.1335521769483 | | 2002 | 1.1588335781108 | | 2001 | 1.1593842684739 | | 2000 | 1.1771701547459 | | 1999 | 1.262148619313 | | 1998 | 1.3010135436644 | | 1997 | 1.3108951600948 | | 1996 | 1.380574505264 | | 1995 | 1.4040101452346 | | 1994 | 1.3314326757732 | | 1993 | 1.3848075991215 | | 1992 | 1.4665250212662 | | 1991 | 1.5406171889881 |
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