| Year | Value | | 2022 | 0.7061174269574 | | 2021 | 0.69927820416844 | | 2020 | 0.71947282559554 | | 2019 | 0.70799909760206 | | 2018 | 0.71969310879077 | | 2017 | 0.76020595961281 | | 2016 | 0.79012720053522 | | 2015 | 0.80251504292972 | | 2014 | 0.83386010034124 | | 2013 | 0.85291256582615 | | 2012 | 0.84722341164851 | | 2011 | 0.81369995783056 | | 2010 | 0.7624548830356 | | 2009 | 0.5859120688811 | | 2008 | 0.5841819783476 | | 2007 | 0.74041254913803 | | 2006 | 0.75940783948045 | | 2005 | 0.81215080284732 | | 2004 | 0.87872614211179 | | 2003 | 0.95084548671382 | | 2002 | 1.0063411988268 | | 2001 | 1.0409216084204 | | 2000 | 1.0967126383861 | | 1999 | 1.1734475528276 | | 1998 | 1.2298717075362 | | 1997 | 1.2556361424304 | | 1996 | 1.2587897972318 | | 1995 | 1.2745871649947 | | 1994 | 1.3047538885505 | | 1993 | 1.3260817199517 | | 1992 | 1.3605953348658 | | 1991 | 1.4384486237855 | | 1990 | 1.5332424513362 | | 1989 | 1.5854526063344 | | 1988 | 1.6474746942079 | | 1987 | 1.7435348216089 | | 1986 | 1.8571085810601 | | 1985 | 1.9748000147305 | | 1984 | 2.0552102810941 | | 1983 | 1.9430755884574 | | 1982 | 1.8372727245748 | | 1981 | 1.907001538827 | | 1980 | 1.9431165149792 | | 1979 | 1.9573110320871 | | 1978 | 1.9799863331105 | | 1977 | 1.9625030283424 | | 1976 | 1.9486384962877 | | 1975 | 1.9713694543278 | | 1974 | 1.9912638961666 | | 1973 | 2.125636657126 | | 1972 | 2.256270489334 | | 1971 | 2.2857940324305 | | 1970 | 2.3159782579982 | | 1969 | 2.3353094790355 | | 1968 | 2.3467798975278 | | 1967 | 2.3276848005277 | | 1966 | 2.3110825909108 | | 1965 | 2.2866731920835 | | 1964 | 2.2456653414222 | | 1963 | 2.2260978457613 | | 1962 | 2.2119516583437 | | 1961 | 2.1966739327622 |
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