| Year | Value | | 2020 | 0.88275371136143 | | 2019 | 0.81408897780156 | | 2018 | 0.83150907990033 | | 2017 | 0.83306590710373 | | 2016 | 0.86471708767617 | | 2015 | 0.90331718344616 | | 2014 | 0.94705347071237 | | 2013 | 0.95558528487553 | | 2012 | 0.96503830790632 | | 2011 | 0.93072405763713 | | 2010 | 0.93849679298949 | | 2009 | 1.0174426991274 | | 2008 | 0.72991018263121 | | 2007 | 0.75220534730904 | | 2006 | 0.64863672775744 | | 2005 | 1.9273472116002 | | 2004 | 1.0302022328191 | | 2003 | 1.1021950255369 | | 2002 | 1.0893518315649 | | 2001 | 1.1033025937528 | | 2000 | 1.1219650844466 | | 1999 | 1.3020625510849 | | 1998 | 1.2149287686463 | | 1997 | 1.472052461718 | | 1996 | 1.353948037503 | | 1995 | 1.3887393594066 | | 1994 | 1.5161372131744 | | 1993 | 1.487875211906 | | 1992 | 1.67570227053 | | 1991 | 1.9157723669928 |
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