Year | Value | 2014 | 2.373 | 2013 | 2.402 | 2012 | 2.441 | 2011 | 2.497 | 2010 | 2.535 | 2009 | 2.561 | 2008 | 2.595 | 2007 | 2.623 | 2006 | 2.639 | 2005 | 2.655 | 2004 | 2.705 | 2003 | 2.765 | 2002 | 2.829 | 2001 | 2.893 | 2000 | 2.944 | 1998 | 3.047 | 1997 | 3.074 | 1996 | 3.125 | 1995 | 3.223 | 1994 | 3.281 | 1993 | 3.311 | 1992 | 3.341 | 1991 | 3.35 | 1990 | 3.361 | 1987 | 3.319 | 1986 | 3.255 | 1985 | 2.694 | 1980 | 2.669 |
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