| Year | Value | | 2022 | 0.1851630776433 | | 2021 | 0.26885196996991 | | 2020 | 0.66975465616498 | | 2019 | 0.69630404633336 | | 2018 | 0.36258439513476 | | 2017 | 0.065159039249015 | | 2016 | 0.073197207241528 | | 2015 | 0.075190689011533 | | 2014 | 0.098351921945115 | | 2013 | 0.13572622891563 | | 2012 | 0.21002430590045 | | 2011 | 0.20773270232972 | | 2010 | 0.43607948463593 | | 2009 | 0.90387553521091 | | 2008 | 0.15814084363436 | | 2007 | 0.55920781553683 | | 2006 | 0.31911453657107 | | 2005 | 0.17320890507374 | | 2004 | 0.064066202261692 | | 2003 | 0.060296779257292 | | 2002 | 0.12391544232327 | | 2001 | 0.15749874204766 | | 2000 | 0.29607496005045 | | 1999 | 0.071430844513726 | | 1998 | 0.21811765673508 | | 1997 | 0.13445434302237 | | 1996 | 0.062536133745972 | | 1995 | 0.021561499989935 | | 1994 | 0.11569409324114 | | 1993 | 0.23830047754197 | | 1992 | 0.14669940294923 | | 1991 | 0.063438223655983 | | 1990 | 0.090624342792107 | | 1989 | 0.057872300250323 | | 1988 | 0.27202215434159 | | 1987 | 1.2039359321304 | | 1986 | 1.2449218453194 | | 1985 | 0.48980490535953 | | 1984 | 0.51021326280994 | | 1983 | 0.62552142498041 | | 1982 | 0.19927355347776 | | 1981 | 0.27396083047318 | | 1980 | 0.98924830905971 | | 1979 | 1.0707826198988 | | 1978 | 1.0888857022045 | | 1977 | 1.2083280812079 | | 1976 | 1.4759124858136 | | 1975 | 0.97762139269238 | | 1974 | 0.53262645784994 | | 1973 | 0.82207270146094 | | 1972 | 0.79632159823407 | | 1971 | 0.77638984758827 | | 1970 | 0.64075548596666 | | 1969 | 0.545750560339 | | 1968 | 0.88495996325432 | | 1967 | 1.1682461402419 | | 1966 | 1.2500671210412 | | 1965 | 1.0389960329135 | | 1964 | 0.93214610558489 | | 1963 | 0.82729884198167 | | 1962 | 0.59528973897018 | | 1961 | 0.59210246058327 |
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