| Year | Value | | 2020 | 0.91039212611966 | | 2019 | 0.60675438986801 | | 2018 | 0.68983237073391 | | 2017 | 0.60021067394656 | | 2016 | 0.52879439856359 | | 2015 | 0.52579150930879 | | 2014 | 0.52749846518808 | | 2013 | 0.51997904415905 | | 2012 | 0.51062454863579 | | 2011 | 0.51771103982504 | | 2010 | 0.4339716805176 | | 2009 | 0.5195225637376 | | 2008 | 0.43443392824715 | | 2007 | 1.4944200990713 | | 2006 | 1.5153446473125 | | 2005 | 0.45684963799235 | | 2004 | 0.45396520447501 | | 2003 | 0.73556053799443 | | 2002 | 0.77595502671693 | | 2001 | 0.91057265914534 | | 2000 | 0.77579235780639 | | 1999 | 0.83778229717246 | | 1998 | 0.75222373976525 | | 1997 | 0.69370874681087 | | 1996 | 1.0483073671292 | | 1995 | 0.95497019732389 | | 1994 | 0.50170831681877 | | 1993 | 0.41117203766994 | | 1992 | 0.40665019462278 |
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