Year | Value | 2022 | 2.223630776646 | 2021 | 2.2661428347073 | 2020 | 2.2763085549341 | 2019 | 2.2523309029981 | 2018 | 2.2314378001065 | 2017 | 2.2100760278057 | 2016 | 2.1707262832354 | 2015 | 2.1294667336857 | 2014 | 2.1290474309562 | 2013 | 2.1674016846136 | 2012 | 2.2762299164507 | 2011 | 2.3777843715679 | 2010 | 2.3912239789074 | 2009 | 2.3336962370184 | 2008 | 2.329977948933 | 2007 | 2.3803874126887 | 2006 | 2.3921751705119 | 2005 | 2.3842735013859 | 2004 | 2.4101599314063 | 2003 | 2.4742860392012 | 2002 | 2.5112894818554 | 2001 | 2.4907227913546 | 2000 | 2.4787401535325 | 1999 | 2.4537187629126 | 1998 | 2.4577068081741 | 1997 | 2.4951175884104 | 1996 | 2.5570992777534 | 1995 | 2.5742302386213 | 1994 | 2.6296815304342 | 1993 | 2.6868541960165 | 1992 | 2.6277617273258 | 1991 | 2.5873726330215 | 1990 | 2.6386256679554 | 1989 | 2.6775393223994 | 1988 | 2.6910651330236 | 1987 | 2.7352501408955 | 1986 | 2.7546420993702 | 1985 | 2.7786720432898 | 1984 | 2.7661114486856 | 1983 | 2.8246083673678 | 1982 | 2.8220287320838 | 1981 | 2.7300327702067 | 1980 | 2.7578750706992 | 1979 | 2.809452861806 | 1978 | 2.7336316308627 | 1977 | 2.6186568430557 | 1976 | 2.5933783598419 | 1975 | 2.6405823419668 | 1974 | 2.671756850166 | 1973 | 2.6360757810482 | 1972 | 2.4422262801424 | 1971 | 2.4141789228954 | 1970 | 2.6135341457598 | 1969 | 2.6774439288774 | 1968 | 2.6837962608491 | 1967 | 2.6557999665399 | 1966 | 2.6344497613033 | 1965 | 2.625887093118 | 1964 | 2.5929635685419 | 1963 | 2.558402993977 | 1962 | 2.5302828142884 | 1961 | 2.49873560053 |
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