| Year | Value | | 2020 | 1.0684279539605 | | 2019 | 1.1160431198478 | | 2018 | 1.1064861704668 | | 2017 | 1.1449138244181 | | 2016 | 1.1497658221147 | | 2015 | 0.67016096925722 | | 2014 | 0.73853856986387 | | 2013 | 0.83595750785481 | | 2012 | 0.92872507297969 | | 2011 | 0.97866672417025 | | 2010 | 0.97913204093436 | | 2009 | 0.98641588296761 | | 2008 | 1.1434277677622 | | 2007 | 1.3912817647018 | | 2006 | 1.8451063934474 | | 2005 | 2.2728607172012 | | 2004 | 2.4213710206281 | | 2003 | 2.5710885242367 | | 2002 | 2.7134013580136 | | 2001 | 2.842563576361 | | 2000 | 3.0157111193927 | | 1999 | 3.0711571495497 | | 1998 | 3.2735948510237 | | 1997 | 3.4713948240915 | | 1996 | 3.5921836519113 | | 1995 | 3.4831506509726 | | 1994 | 3.2401782098015 | | 1993 | 2.6802196439998 | | 1992 | 2.7772281180461 | | 1991 | 3.9383469683679 | | 1990 | 4.0858777208231 |
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