Year | Value | 2022 | 1.7883385403946 | 2021 | 1.6233351872385 | 2020 | 1.7578990069759 | 2019 | 2.0626869010708 | 2018 | 2.0961940152886 | 2017 | 2.0687388460712 | 2016 | 2.1096971284513 | 2015 | 2.1559663132242 | 2014 | 2.2592256749777 | 2013 | 2.2998234980849 | 2012 | 2.157196193329 | 2011 | 2.1742048828725 | 2010 | 2.4378449334 | 2009 | 2.6323322674806 | 2008 | 2.7058575141175 | 2007 | 2.6757174333185 | 2006 | 2.5406584279399 | 2005 | 2.3333270422908 | 2004 | 2.1777935778166 | 2003 | 2.1846765192764 | 2002 | 2.2167074815321 | 2001 | 2.2456015007727 | 2000 | 2.2859343173938 | 1999 | 2.2866822574159 | 1998 | 2.3185728820805 | 1997 | 2.3687981822624 | 1996 | 2.4043528061863 | 1995 | 2.4868788664302 | 1994 | 2.7169136718256 | 1993 | 2.70328023527 | 1992 | 2.4958131508443 | 1991 | 2.1749613310183 | 1990 | 3.1512686832507 | 1989 | 2.607711150172 | 1988 | 2.6748980744415 | 1987 | 2.9604363668773 | 1986 | 3.0412807525442 | 1985 | 3.0473060204385 | 1984 | 3.156908917766 | 1983 | 3.2223023856607 | 1982 | 3.1592030933818 | 1981 | 3.2267814034564 | 1980 | 3.5137507046055 | 1979 | 3.3639712168454 | 1978 | 3.1463009240083 | 1977 | 3.5043980322982 | 1976 | 3.5689590921796 | 1975 | 3.1912985462665 | 1974 | 2.9893732938343 | 1973 | 2.9160948033402 | 1972 | 2.8780772848719 | 1971 | 2.8611312207892 | 1970 | 2.8671732245961 | 1969 | 2.8793593742489 | 1968 | 2.870968689321 | 1967 | 2.8385585912627 | 1966 | 2.7718144235759 | 1965 | 2.7268616566869 | 1964 | 2.7019459433197 | 1963 | 2.6700510476975 | 1962 | 2.6193879328843 | 1961 | 2.5717183486395 |
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