| Year | Value | | 2020 | 0.62258790170227 | | 2019 | 0.70475041566455 | | 2018 | 0.71328118531897 | | 2017 | 0.74332364831163 | | 2016 | 0.78085143751571 | | 2015 | 0.83388820323577 | | 2014 | 0.8525390856801 | | 2013 | 0.91139134109811 | | 2012 | 0.94560804701836 | | 2011 | 0.96339756379656 | | 2010 | 0.91992077769784 | | 2009 | 0.90281651371373 | | 2008 | 0.86262218343805 | | 2007 | 0.86426616073225 | | 2005 | 0.90487646342925 | | 2004 | 0.92115134110349 | | 2003 | 0.99725370081868 | | 2002 | 1.0211901525809 | | 2001 | 0.99085340143131 | | 2000 | 1.2475656478032 | | 1999 | 1.2749161021177 | | 1998 | 1.2269453557109 | | 1997 | 1.2652671392005 | | 1996 | 1.2352261133173 | | 1995 | 1.2257317725804 | | 1994 | 0.71941102063114 | | 1993 | 0.76773879380123 | | 1992 | 0.76847825909738 | | 1991 | 0.83433372838191 |
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