Year | Value | 2021 | 2.2071540340956 | 2020 | 2.2084274675048 | 2019 | 2.196700027938 | 2018 | 2.1999244059292 | 2017 | 2.195123287221 | 2016 | 2.2049333563342 | 2015 | 2.2101904566573 | 2014 | 2.2135368165036 | 2013 | 2.2123799062102 | 2012 | 2.2228975698437 | 2011 | 2.239598733997 | 2010 | 2.2604067417945 | 2009 | 2.2858144144736 | 2008 | 2.3137957091698 | 2007 | 2.334329927391 | 2006 | 2.3491145645103 | 2005 | 2.3600661475616 | 2004 | 2.3792314179015 | 2003 | 2.3847072094271 | 2002 | 2.4038724797669 | 2001 | 2.4120861670554 | 2000 | 2.4066103755298 | 1999 | 2.4148240628183 | 1998 | 2.4586303950236 | 1997 | 2.4558924992608 | 1996 | 2.7242062840183 | 1995 | 2.7023031179157 | 1994 | 2.4531546034979 | 1993 | 2.4230377501068 | 1992 | 2.4038724797669 | 1991 | 2.4285135416324 | 1990 | 2.354590356036 | 1989 | 2.4038724797669 | 1988 | 2.3819693136643 | 1987 | 2.3682798348501 | 1986 | 2.3682798348501 | 1985 | 2.338162981459 | 1984 | 2.3326871899333 | 1983 | 2.3162598153563 | 1982 | 2.2943566492537 | 1981 | 2.2587640043368 | 1980 | 2.2313850467085 | 1979 | 2.2669776916253 | 1978 | 2.2012681933173 | 1977 | 2.1848408187404 | 1976 | 2.1711513399262 | 1975 | 2.1629376526377 | 1974 | 2.1656755484005 | 1973 | 2.157461861112 | 1972 | 2.1711513399262 | 1971 | 2.2012681933173 | 1970 | 2.22317135942 | 1969 | 2.2587640043368 | 1968 | 2.3025703365421 | 1967 | 2.3080461280678 | 1966 | 2.3162598153563 | 1965 | 2.321735606882 | 1964 | 2.3272113984076 | 1963 | 2.3326871899333 | 1962 | 2.338162981459 | 1961 | 2.3436387729846 |
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