Year | Value | 2022 | 2.3786951498171 | 2021 | 2.4168693737005 | 2020 | 2.4824228929206 | 2019 | 2.5253166282828 | 2018 | 2.5540770406726 | 2017 | 2.584164851898 | 2016 | 2.5860114844229 | 2015 | 2.588187143176 | 2014 | 2.6271377711217 | 2013 | 2.6715891397262 | 2012 | 2.7281409974369 | 2011 | 2.8001650109023 | 2010 | 2.8659491482712 | 2009 | 2.8994727895916 | 2008 | 2.9114915298736 | 2007 | 2.9265245216625 | 2006 | 2.9267524620721 | 2005 | 2.9232856843983 | 2004 | 2.9270346495312 | 2003 | 2.9334163157818 | 2002 | 2.9615685904138 | 2001 | 2.996230704661 | 2000 | 3.0399010076765 | 1999 | 3.0985230327836 | 1998 | 3.1440056235649 | 1997 | 3.1721338414649 | 1996 | 3.1813268555858 | 1995 | 3.171940650751 | 1994 | 3.1452360123461 | 1993 | 3.094667743784 | 1992 | 3.0408716469539 | 1991 | 3.005014484009 | 1990 | 2.955257306945 | 1989 | 2.9016450051425 | 1988 | 2.8627620277736 | 1987 | 2.8130428428024 | 1986 | 2.7836670332104 | 1985 | 2.7839369766112 | 1984 | 2.7835514048933 | 1983 | 2.8016710132534 | 1982 | 2.8235708616136 | 1981 | 2.8549585704178 | 1980 | 2.9011837262364 | 1979 | 2.9345121869902 | 1978 | 2.9549649251637 | 1977 | 2.9716113902172 | 1976 | 2.989979850555 | 1975 | 3.0098518653529 | 1974 | 3.026891097495 | 1973 | 3.0375982845901 | 1972 | 3.0327672534296 | 1971 | 2.9780079482876 | 1970 | 2.8944100680992 | 1969 | 2.826980047857 | 1968 | 2.7649006542212 | 1967 | 2.7098390508794 | 1966 | 2.6631111258981 | 1965 | 2.6368348295695 | 1964 | 2.6232992515685 | 1963 | 2.607152195817 | 1962 | 2.5951476460454 | 1961 | 2.5857942043094 |
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