| Year | Value | | 2022 | 0.29693509598903 | | 2021 | 0.37632294450367 | | 2020 | 0.49749135031436 | | 2019 | 0.62186020547766 | | 2018 | 0.69224615834578 | | 2017 | 0.74994474009631 | | 2016 | 0.75384682684643 | | 2015 | 0.7925202851188 | | 2014 | 0.83203575702491 | | 2013 | 0.86901210309547 | | 2012 | 0.86093776043708 | | 2011 | 0.7785533574302 | | 2010 | 0.73753239923333 | | 2009 | 0.76301230846529 | | 2008 | 0.74903186085038 | | 2007 | 0.69792779907031 | | 2006 | 0.74350258909026 | | 2005 | 0.78603922794697 | | 2004 | 0.79189073968151 | | 2003 | 0.81506284798014 | | 2002 | 0.85031189976144 | | 2001 | 0.89448404899211 | | 2000 | 0.94227808778686 | | 1999 | 0.99844996169595 | | 1998 | 1.0750416335613 | | 1997 | 1.1339326302059 | | 1996 | 1.1629089307188 | | 1995 | 1.1896384629051 | | 1994 | 1.2440930438518 | | 1993 | 1.2653735452536 | | 1992 | 1.323391378473 | | 1991 | 1.4396849790019 | | 1990 | 1.6049371884441 | | 1989 | 1.5912087505245 | | 1988 | 1.6773867713222 | | 1987 | 1.6945280451992 | | 1986 | 1.6400925552375 | | 1985 | 1.5878244274264 | | 1984 | 1.5831859063142 | | 1983 | 1.6531756524489 | | 1982 | 1.6657247103471 | | 1981 | 1.5719231336788 | | 1980 | 1.5802069074553 | | 1979 | 1.6340303446287 | | 1978 | 1.6458705600953 | | 1977 | 1.6590997983442 | | 1976 | 1.7603688373472 | | 1975 | 1.8836537542897 | | 1974 | 2.0674656654005 | | 1973 | 2.1983865315921 | | 1972 | 2.2994887369881 | | 1971 | 2.4703995856816 | | 1970 | 2.4904386672727 | | 1969 | 2.4917153512538 | | 1968 | 2.4268719247484 | | 1967 | 2.406521560668 | | 1966 | 2.5181372633461 | | 1965 | 2.36503092567 | | 1964 | 2.3675074896411 | | 1963 | 2.4461671742442 | | 1962 | 1.5337514037176 | | 1961 | 0.49194549814445 |
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