Year | Value | 2021 | 24.927119981979 | 2020 | 24.75897820411 | 2019 | 24.576704903603 | 2018 | 24.238180702264 | 2017 | 24.683679444024 | 2016 | 25.070309545988 | 2015 | 24.739527170909 | 2014 | 24.84107219491 | 2013 | 25.138903933917 | 2012 | 24.94682978581 | 2011 | 23.64758929127 | 2010 | 23.680622988167 | 2009 | 23.742944946346 | 2008 | 23.48996403125 | 2007 | 23.763347918475 | 2006 | 23.327821167798 | 2005 | 21.959309611925 | 2004 | 22.215849272784 | 2003 | 22.763572662432 | 2002 | 22.891387718311 | 2001 | 23.405750071618 | 2000 | 23.809740519007 | 1999 | 24.993075349136 | 1998 | 24.644377810331 | 1997 | 25.775632203859 | 1996 | 24.290623514697 | 1995 | 24.363031286226 | 1994 | 25.094003269727 | 1993 | 26.274937840387 | 1992 | 25.497805235913 | 1991 | 24.808523275337 | 1990 | 24.177729660637 | 1989 | 23.947673494336 | 1988 | 23.24040591564 | 1987 | 21.492338654927 | 1986 | 22.176390590405 | 1985 | 20.396108723498 | 1984 | 20.955834436927 | 1983 | 21.128336541352 | 1982 | 19.388292337816 | 1981 | 17.7843394527 | 1980 | 17.368251501641 | 1979 | 15.779849818803 | 1978 | 15.621981919849 | 1977 | 14.90944062829 | 1976 | 14.0733844475 | 1975 | 12.713823619769 | 1974 | 13.498170699614 | 1973 | 12.550606468996 |
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