| Year | Value | | 2014 | 143.50683811358 | | 2013 | 134.3240002257 | | 2012 | 119.38957715454 | | 2011 | 114.86665327534 | | 2010 | 101.98233408257 | | 2009 | 96.422306912203 | | 2008 | 82.807743483782 | | 2007 | 86.547497899482 | | 2006 | 82.39384552289 | | 2005 | 75.47999608904 | | 2004 | 72.75813515362 | | 2003 | 68.878493042922 | | 2002 | 65.924059115643 | | 2001 | 62.910543891304 | | 2000 | 57.330157372911 | | 1999 | 53.514128247602 | | 1998 | 47.841383285925 | | 1997 | 45.162422782472 | | 1996 | 44.768319338918 | | 1995 | 42.410929538634 | | 1994 | 39.826103083261 | | 1993 | 37.05208531064 | | 1992 | 35.64850056755 | | 1991 | 35.865477436318 | | 1990 | 33.899981291288 | | 1989 | 31.496347598915 | | 1988 | 29.058672611587 | | 1987 | 26.901370300145 | | 1986 | 24.69765443644 | | 1985 | 21.32199687228 | | 1984 | 19.251400539389 | | 1983 | 17.860701343746 | | 1982 | 16.761358144711 | | 1981 | 13.588154435574 | | 1980 | 11.922739112135 | | 1979 | 11.155906816417 | | 1978 | 10.141872028381 | | 1977 | 9.4842557917532 | | 1976 | 8.6432622116998 | | 1975 | 6.3911341038743 | | 1974 | 6.8984238642607 | | 1973 | 5.5489056170897 | | 1972 | 7.2784553125828 | | 1971 | 5.7926225472353 |
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