Year | Value | 2020 | 3.279 | 2019 | 3.224 | 2018 | 3.13 | 2017 | 3.054 | 2016 | 2.978 | 2015 | 2.802 | 2014 | 2.753 | 2013 | 2.613 | 2012 | 2.526 | 2011 | 2.479 | 2010 | 2.42 | 2009 | 2.403 | 2008 | 2.386 | 2007 | 2.379 | 2006 | 2.354 | 2005 | 2.34 | 2004 | 2.298 | 2003 | 2.254 | 2002 | 2.238 | 2001 | 2.182 | 2000 | 2.156 | 1999 | 2.123 | 1998 | 2.18 | 1997 | 2.229 | 1996 | 2.135 | 1995 | 2.117 | 1994 | 2.187 | 1993 | 2.028 | 1992 | 2.094 | 1991 | 2.088 | 1990 | 2.07 | 1989 | 2.063 | 1988 | 2.024 | 1987 | 2.004 | 1986 | 1.882 | 1985 | 1.879 | 1984 | 1.861 | 1982 | 1.843 | 1980 | 1.771 |
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