| Year | Value | | 2022 | 1.6053429000147 | | 2021 | 1.4663195733746 | | 2020 | 1.2658347695359 | | 2019 | 1.1591162855326 | | 2018 | 0.94310873267023 | | 2017 | 0.89504140654103 | | 2016 | 0.97011597790921 | | 2015 | 0.99342769175221 | | 2014 | 1.0929608002562 | | 2013 | 1.1694371885529 | | 2012 | 1.2253196617163 | | 2011 | 1.2621870998274 | | 2010 | 1.3821546110286 | | 2009 | 1.6881645622478 | | 2008 | 1.7423408689423 | | 2007 | 1.9500696947165 | | 2006 | 1.8365376873582 | | 2005 | 2.0292633057744 | | 2004 | 2.3801040713039 | | 2003 | 2.3417011586725 | | 2002 | 2.6455975187613 | | 2001 | 6.1003956276616 | | 2000 | 1.850821459557 | | 1999 | 1.7138206058622 | | 1998 | 2.0982397612045 | | 1997 | 2.1282469441278 | | 1996 | 2.8136767423194 | | 1992 | 4.3520309477756 |
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