Year | Value | 2022 | 2.5421545264726 | 2021 | 2.5936661188055 | 2020 | 2.6528516097025 | 2019 | 2.6679760162315 | 2018 | 2.6806178915115 | 2017 | 2.6761689643624 | 2016 | 2.7220405166756 | 2015 | 2.7704541954546 | 2014 | 2.7651551873959 | 2013 | 2.772759552481 | 2012 | 2.7697659286108 | 2011 | 2.7829969117016 | 2010 | 2.7937984074131 | 2009 | 2.7914689005243 | 2008 | 2.7929546870629 | 2007 | 2.7799753841469 | 2006 | 2.7551397368333 | 2005 | 2.7368497119354 | 2004 | 2.7190100547874 | 2003 | 2.6977773031215 | 2002 | 2.6889843729076 | 2001 | 2.6741898242936 | 2000 | 2.6502016542675 | 1999 | 2.6184528884921 | 1998 | 2.5976644244307 | 1997 | 2.6238646256199 | 1996 | 2.6908571649016 | 1995 | 2.6535627204986 | 1994 | 2.6242170506517 | 1993 | 2.6636610464309 | 1992 | 2.6723569765023 | 1991 | 2.7267660622709 | 1990 | 2.8083837468768 | 1989 | 2.8136578086739 | 1988 | 2.8436722063954 | 1987 | 2.922360988775 | 1986 | 2.897063296849 | 1985 | 2.8633582403213 | 1984 | 2.8083836324557 | 1983 | 2.8942714890141 | 1982 | 3.0353531470461 | 1981 | 2.9494597963499 | 1980 | 2.9164993043239 | 1979 | 3.0237033909826 | 1978 | 2.9317905642373 | 1977 | 2.8236052691969 | 1976 | 2.8584355964236 | 1975 | 2.8601579235282 | 1974 | 2.8267127222903 | 1973 | 2.7427868067511 | 1972 | 2.6914696060461 | 1971 | 2.7011387521568 | 1970 | 2.6863530038886 | 1969 | 2.6596447663438 | 1968 | 2.6372731299381 | 1967 | 2.5983301283582 | 1966 | 2.5865953976168 | 1965 | 2.5888159262747 | 1964 | 2.5552223785803 | 1963 | 2.5148049807393 | 1962 | 2.4829860932431 | 1961 | 2.4279111470389 |
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