Year | Value | 2019 | 2.168 | 2014 | 2.225 | 2013 | 2.266 | 2012 | 2.258 | 2011 | 2.272 | 2010 | 2.313 | 2009 | 2.307 | 2008 | 2.313 | 2007 | 2.309 | 2006 | 2.392 | 2005 | 2.46 | 2004 | 2.512 | 2003 | 2.541 | 2002 | 2.568 | 2001 | 2.686 | 2000 | 2.796 | 1999 | 2.893 | 1998 | 2.969 | 1997 | 3.029 | 1996 | 3.206 | 1995 | 3.128 | 1994 | 3.084 | 1993 | 3.117 | 1992 | 3.376 | 1991 | 3.446 | 1990 | 3.423 | 1981 | 3.088 |
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