Year | Value | 2015 | 81.448329173173 | 2014 | 81.704295651735 | 2013 | 83.473068522982 | 2012 | 82.446824627073 | 2011 | 81.950301609193 | 2010 | 82.019950711663 | 2009 | 80.662009500227 | 2008 | 80.297284863402 | 2007 | 80.829527635221 | 2006 | 79.519432349017 | 2005 | 79.560496136962 | 2004 | 81.605740790957 | 2003 | 81.260035803816 | 2002 | 82.437516807583 | 2001 | 81.711186348262 | 2000 | 81.693805168524 | 1999 | 82.278005815261 | 1998 | 82.681079226621 | 1997 | 86.142024206944 | 1996 | 85.701198868917 | 1995 | 85.390131170747 | 1994 | 85.409985048825 | 1993 | 83.86996456003 | 1992 | 81.605456658205 | 1991 | 77.773777487514 | 1990 | 75.651712187284 | 1989 | 72.24319162656 | 1988 | 71.024361649535 | 1987 | 67.473473634125 | 1986 | 69.787516029887 | 1985 | 72.526650728877 | 1984 | 75.032535194955 | 1983 | 75.759269381345 | 1982 | 76.770385804106 | 1981 | 75.99097978769 | 1980 | 77.526899685333 | 1979 | 77.374220272 | 1978 | 74.823766393678 | 1977 | 74.151971441557 | 1976 | 71.272652142577 | 1975 | 65.60523409285 | 1974 | 67.376369847357 | 1973 | 68.647673247657 | 1972 | 66.459694619317 | 1971 | 62.418077725821 |
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