| Year | Value | | 2020 | 0.67942827081623 | | 2019 | 0.6804466840861 | | 2018 | 0.70030175761252 | | 2017 | 0.68246408532751 | | 2016 | 1.3277821310702 | | 2015 | 1.310466357251 | | 2014 | 1.3357676178384 | | 2013 | 1.3450640121423 | | 2012 | 1.3375239125585 | | 2011 | 1.1870437607116 | | 2010 | 1.163005282543 | | 2009 | 1.1616933072064 | | 2008 | 1.1608896284186 | | 2007 | 1.1583995551746 | | 2006 | 1.076281974136 | | 2005 | 1.1810116939841 | | 2004 | 0.99358245094932 | | 2003 | 1.1445004671643 | | 2002 | 1.389565086714 | | 2001 | 1.2380201091299 | | 2000 | 1.4078690494068 | | 1999 | 1.46500667334 | | 1998 | 1.431791686029 | | 1997 | 1.4679194305517 | | 1996 | 1.4960336474472 | | 1995 | 1.3812317374932 | | 1994 | 1.8315274831472 | | 1993 | 1.2982081482034 | | 1992 | 1.6275617822452 |
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