| Year | Value | | 2020 | 0.53869635482133 | | 2018 | 0.56040722925326 | | 2017 | 0.57417586623999 | | 2016 | 0.58773197658672 | | 2015 | 0.60058436859064 | | 2014 | 0.61283271709599 | | 2013 | 0.62471464856938 | | 2012 | 0.63631244213534 | | 2011 | 0.65127451709351 | | 2010 | 0.6710542429921 | | 2009 | 0.70041540470294 | | 2008 | 0.73059672096015 | | 2007 | 0.75504891773176 | | 2005 | 0.8195484151641 | | 2004 | 0.85399770559283 | | 2003 | 0.8881198428916 | | 2002 | 0.9153080698136 | | 2001 | 0.93740918848487 | | 2000 | 1.2282577900203 | | 1999 | 1.2894174927535 | | 1998 | 1.3280541704442 | | 1997 | 1.354447056019 | | 1996 | 1.3789033306031 | | 1995 | 1.5781038562432 | | 1994 | 0.97145099806876 | | 1993 | 1.0010160312717 | | 1992 | 1.0320151747511 | | 1991 | 0.95594678562893 |
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