| Year | Value | | 2022 | 0.7244968998201 | | 2021 | 0.76700448127761 | | 2020 | 0.35932613287235 | | 2019 | 0.032018784627038 | | 2018 | 0.042693991469295 | | 2017 | 0.15432468221087 | | 2016 | 0.21883668537547 | | 2015 | 0.25929837102844 | | 2014 | 0.29229212942513 | | 2013 | 0.397066313446 | | 2012 | 0.44753584052461 | | 2011 | 0.45015413902711 | | 2010 | 0.19727763352151 | | 2009 | 0.088064262231673 | | 2008 | 0.023066090521347 | | 2007 | 0.053424317834046 | | 2006 | 0.14888868006219 | | 2005 | 0.25941299554709 | | 2004 | 0.37814388241775 | | 2003 | 0.50437600022459 | | 2002 | 0.64118805112818 | | 2001 | 0.83056129713629 | | 2000 | 1.1256212236042 | | 1999 | 1.2950058977572 | | 1998 | 1.3048687335242 | | 1997 | 1.3497013343119 | | 1996 | 1.433438908026 | | 1995 | 1.5110864594079 | | 1994 | 1.5693066036638 | | 1993 | 1.6404144595445 | | 1992 | 1.7146578050594 | | 1991 | 1.7749442681216 | | 1990 | 1.8276413572442 | | 1989 | 1.9938318114031 | | 1988 | 2.1418160709914 | | 1987 | 2.1706495174722 | | 1986 | 2.2107929528095 | | 1985 | 2.2632374198146 | | 1984 | 2.3391617351653 | | 1983 | 2.4468184317304 | | 1982 | 2.5876514633801 | | 1981 | 2.62646692916 | | 1980 | 2.2892101846145 | | 1979 | 1.9485394012966 | | 1978 | 1.9428844167758 | | 1977 | 2.0325546509361 | | 1976 | 2.1008590913976 | | 1975 | 2.183952212832 | | 1974 | 2.3168022509813 | | 1973 | 2.4320704890158 | | 1972 | 2.520316686267 | | 1971 | 2.4664990188602 | | 1970 | 2.020270731752 | | 1969 | 1.7345113714666 | | 1968 | 1.8585204368729 | | 1967 | 1.9364534485117 | | 1966 | 2.0033482358702 | | 1965 | 2.0570226042538 | | 1964 | 2.0885366870254 | | 1963 | 2.0787058908052 | | 1962 | 2.0619010942585 | | 1961 | 2.0500283729781 |
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