| Year | Value | | 2012 | 8.4724232909821E-5 | | 2011 | 0.00010144628159433 | | 2010 | 0.00012030877648514 | | 2009 | 9.6339670556863E-5 | | 2008 | 0.026956176436725 | | 2007 | 0.010623003073043 | | 2006 | 0.00010433557540548 | | 2005 | 0.0022059530187541 | | 2004 | 0.0061795575530897 | | 2003 | 0.0021040937247509 | | 2002 | 0.0024034154004319 | | 2001 | 0.009502019584538 | | 2000 | 0.0086400074832461 | | 1999 | 0.012601101269929 | | 1998 | 0.0012879446486847 | | 1997 | 0.0010677497076047 | | 1996 | 0.0007391580820495 | | 1995 | 0.21507188013425 | | 1994 | 2.3915031300556 | | 1993 | 2.4492618826167 | | 1992 | 2.6109467455621 | | 1991 | 2.7479383680556 | | 1990 | 2.7355801721858 | | 1989 | 2.927575979845 | | 1988 | 2.8238604757698 | | 1987 | 2.6889064634409 | | 1986 | 2.4987120041216 | | 1985 | 2.4663332050789 | | 1984 | 2.4033802380122 | | 1983 | 2.4142802106074 | | 1982 | 2.3104399330831 | | 1981 | 2.2809963616009 | | 1980 | 2.4691983978097 | | 1979 | 2.3343332424325 | | 1978 | 2.4231678486998 | | 1977 | 3.5607147515325 | | 1976 | 4.2423361906145 | | 1975 | 5.0214865510107 | | 1974 | 6.2639451285018 | | 1973 | 7.0844427538988 | | 1972 | 8.0684060513045 |
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