| Year | Value | | 2021 | 5.7005558017122 | | 2020 | 5.7005558017122 | | 2019 | 5.6986858978981 | | 2018 | 5.6988191897974 | | 2017 | 5.6991242502668 | | 2016 | 5.6988311920223 | | 2015 | 5.6982986242945 | | 2014 | 5.7007745245771 | | 2013 | 5.7001579142009 | | 2012 | 5.6986118181611 | | 2011 | 5.6982885537181 | | 2010 | 5.6994128192333 | | 2009 | 5.6992014972678 | | 2008 | 5.5345602974402 | | 2007 | 5.5356983720569 | | 2006 | 5.5370056225648 | | 2005 | 5.1228946906534 | | 2004 | 4.9428585303055 | | 2003 | 5.9108910891089 | | 2002 | 5.5643564356436 | | 2001 | 5.5643564356436 | | 2000 | 5.5445544554456 | | 1999 | 4.9306930693069 | | 1998 | 4.9306930693069 | | 1997 | 3.8712871287129 | | 1996 | 3.6534653465347 | | 1995 | 4.3366336633663 | | 1994 | 4.3267326732673 | | 1993 | 4.9306930693069 |
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