Year | Value | 2022 | 1.463315729907 | 2021 | 1.4945571670494 | 2020 | 1.6266329046917 | 2019 | 1.6551836920487 | 2018 | 1.7002477655515 | 2017 | 1.761022620012 | 2016 | 1.7738244699361 | 2015 | 1.6698300209423 | 2014 | 1.6168406041295 | 2013 | 1.6869560570809 | 2012 | 1.7435251509336 | 2011 | 1.7816588021712 | 2010 | 1.8016439037615 | 2009 | 1.8400428498718 | 2008 | 1.8704315768842 | 2007 | 1.8703486311163 | 2006 | 1.8840198280479 | 2005 | 1.935755520387 | 2004 | 1.9871267301366 | 2003 | 2.0183125052847 | 2002 | 2.0626781898304 | 2001 | 2.1168672092615 | 2000 | 2.2167940636858 | 1999 | 2.3314503723035 | 1998 | 2.4090179387256 | 1997 | 2.4695964891077 | 1996 | 2.4174588833619 | 1995 | 2.337836526293 | 1994 | 2.3435152690634 | 1993 | 2.3576582789843 | 1992 | 2.3574306755221 | 1991 | 2.3771088092845 | 1990 | 2.3529711094252 | 1989 | 2.3072731517779 | 1988 | 2.3083323756367 | 1987 | 2.2997478634656 | 1986 | 2.3389973402497 | 1985 | 2.395996687462 | 1984 | 2.4501691214504 | 1983 | 2.484007647772 | 1982 | 2.5030503381604 | 1981 | 2.5685376046717 | 1980 | 2.6479814025976 | 1979 | 2.7160429145809 | 1978 | 2.7487012044316 | 1977 | 2.6604750910546 | 1976 | 2.5154512600646 | 1975 | 2.4018244379765 | 1974 | 2.40147320744 | 1973 | 2.490158794855 | 1972 | 2.5458890656656 | 1971 | 2.6001852028453 | 1970 | 2.5935163917536 | 1969 | 2.5887845661861 | 1968 | 2.6457979826879 | 1967 | 2.6702012642425 | 1966 | 2.7041404709951 | 1965 | 2.7470402687537 | 1964 | 2.7730696332649 | 1963 | 2.8018698530958 | 1962 | 2.8343601205762 | 1961 | 2.9590629376038 |
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