| Year | Value | | 2020 | 0.70404168413427 | | 2019 | 0.8049123655987 | | 2018 | 0.7887643283997 | | 2017 | 0.81501533222717 | | 2016 | 0.86602534928552 | | 2015 | 0.89883794290099 | | 2014 | 0.90840463596533 | | 2013 | 0.94960620472635 | | 2012 | 0.98145747493131 | | 2011 | 0.99674514738482 | | 2010 | 1.0232815669145 | | 2009 | 0.99631325300405 | | 2008 | 0.96047946355478 | | 2007 | 0.96610472549113 | | 2005 | 1.0054208779901 | | 2004 | 1.0367463214321 | | 2003 | 1.1235861453256 | | 2002 | 1.1578582402181 | | 2001 | 1.1116119274225 | | 2000 | 1.3576174331025 | | 1999 | 1.3640363375569 | | 1998 | 1.33077283657 | | 1997 | 1.3779669240638 | | 1996 | 1.41164839498 | | 1995 | 1.4029665721661 | | 1994 | 0.80857650856117 | | 1993 | 0.89051083730969 | | 1992 | 0.8968586738667 | | 1991 | 0.96068520725702 |
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