| Year | Value | | 2022 | 1.2032825680808 | | 2021 | 1.118350040109 | | 2020 | 1.1528792258657 | | 2019 | 1.2008645304274 | | 2018 | 1.1822617288957 | | 2017 | 1.1462890148485 | | 2016 | 1.2535150449188 | | 2015 | 1.2574823592665 | | 2014 | 1.268842470278 | | 2013 | 1.2707966515007 | | 2012 | 1.2292187217811 | | 2011 | 1.2244951097658 | | 2010 | 1.3413834329232 | | 2009 | 1.3725769814511 | | 2008 | 1.4534928515735 | | 2007 | 1.6497659143748 | | 2006 | 1.7094124919576 | | 2005 | 1.4984531353019 | | 2004 | 1.3582223138283 | | 2003 | 1.2990639000234 | | 2002 | 1.4002458005251 | | 2001 | 1.4382907469224 | | 2000 | 1.3469841507577 | | 1999 | 1.3667607383859 | | 1998 | 1.4950987024343 | | 1997 | 1.7689665512635 | | 1996 | 1.260692559907 | | 1995 | 1.6994637694291 | | 1994 | 3.6216082548389 | | 1993 | 2.7909714610482 | | 1992 | 1.6224986479178 |
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