Year | Value | 2014 | 32.692107819325 | 2013 | 30.886160542182 | 2012 | 30.17513513838 | 2011 | 28.342563070429 | 2010 | 27.33268135696 | 2009 | 26.468271021055 | 2008 | 25.150932541051 | 2007 | 24.519103201118 | 2006 | 23.124508462958 | 2005 | 21.754704910332 | 2004 | 21.300208598814 | 2003 | 19.930242548338 | 2002 | 20.919571489557 | 2001 | 20.831403112875 | 2000 | 21.304453976059 | 1999 | 21.08123592072 | 1998 | 18.70037357418 | 1997 | 16.850717762541 | 1996 | 16.019973308453 | 1995 | 14.6983047352 | 1994 | 13.7575259765 | 1993 | 13.309940437751 | 1992 | 12.25819394268 | 1991 | 10.165699211413 | 1990 | 10.080388287029 | 1989 | 9.3976309739413 | 1988 | 8.2215820001438 | 1987 | 7.993247414366 | 1986 | 7.3769439542 | 1985 | 8.2852176499928 | 1984 | 6.5379869055585 | 1983 | 7.180890802433 | 1982 | 8.5577318397244 | 1981 | 9.4450764591057 | 1980 | 10.693318131549 | 1979 | 11.066849135834 | 1978 | 8.899144449771 | 1977 | 9.862892694911 | 1976 | 9.7722652620855 | 1975 | 8.7732278990067 | 1974 | 10.194345700245 | 1973 | 10.857747402048 | 1972 | 10.275013367921 | 1971 | 10.653464589262 |
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