| Year | Value | | 2022 | 0.086392282654993 | | 2021 | 0.045044623090633 | | 2020 | 0.13425530235995 | | 2019 | 0.45196965886331 | | 2018 | 0.49479526304699 | | 2017 | 0.53729570614507 | | 2016 | 0.59006248733308 | | 2015 | 0.63795916173479 | | 2014 | 0.69161526010167 | | 2013 | 0.74930103934763 | | 2012 | 0.8102305877881 | | 2011 | 0.93935590962983 | | 2010 | 1.1315410404899 | | 2009 | 1.2332313205723 | | 2008 | 1.2413973767882 | | 2007 | 1.227710814894 | | 2006 | 1.1815655457307 | | 2005 | 1.0030771839164 | | 2004 | 0.90098922975996 | | 2003 | 0.99739554728492 | | 2002 | 1.1947180554564 | | 2001 | 1.7687566214388 | | 2000 | 2.5392344444525 | | 1999 | 2.9344129255876 | | 1998 | 3.0048045249146 | | 1997 | 3.0273587679625 | | 1996 | 3.0257889363042 | | 1995 | 3.0840609778415 | | 1994 | 3.1960291460615 | | 1993 | 3.0419316103236 | | 1992 | 3.3728641918425 | | 1991 | 3.2224145291231 | | 1990 | 1.7129067847382 | | 1989 | 0.40953147334196 | | 1988 | 0.18325547517955 | | 1987 | 0.15968624278077 | | 1986 | 0.1162511465407 | | 1985 | 0.47259361036967 | | 1984 | 0.76804932646762 | | 1983 | 0.89433478058015 | | 1982 | 0.79854078990286 | | 1981 | 0.55573048430328 | | 1980 | 0.42004358750417 | | 1979 | 0.43315299169455 | | 1978 | 0.44317175200699 | | 1977 | 0.44351032277777 | | 1976 | 0.78420193857444 | | 1975 | 1.1379664472039 | | 1974 | 1.1106292915988 | | 1973 | 0.86280352533116 | | 1972 | 0.066286513122201 | | 1971 | 0.49185153683753 | | 1970 | 0.37826381689548 | | 1969 | 0.23737185075182 | | 1968 | 0.085719333276435 | | 1967 | 0.38884682831593 | | 1966 | 0.86218382371151 | | 1965 | 1.0328409188628 | | 1964 | 1.2157205752687 | | 1963 | 1.3893370634193 | | 1962 | 1.548571743938 | | 1961 | 2.179059041132 |
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