Year | Value | 2023 | 1.51 | 2022 | 1.63 | 2021 | 1.71 | 2020 | 1.77 | 2019 | 1.89 | 2018 | 2 | 2017 | 2.08 | 2016 | 2.11 | 2015 | 2.16 | 2014 | 2.19 | 2013 | 2.11 | 2012 | 2.11 | 2011 | 2.05 | 2010 | 2.08 | 2009 | 2.1 | 2008 | 2.15 | 2007 | 2.16 | 2006 | 2.193 | 2005 | 2.197 | 2004 | 2.197 | 2003 | 2.202 | 2002 | 2.268 | 2001 | 2.392 | 2000 | 2.487 | 1999 | 2.63 | 1998 | 2.707 | 1997 | 2.744 | 1996 | 2.779 | 1995 | 2.835 | 1994 | 2.874 | 1993 | 2.916 | 1992 | 2.939 | 1991 | 3.003 | 1990 | 3.107 | 1989 | 3.336 | 1988 | 3.445 | 1987 | 3.542 | 1986 | 3.658 | 1985 | 3.779 | 1984 | 3.911 | 1983 | 4.056 | 1982 | 4.205 | 1981 | 4.351 | 1980 | 4.453 | 1979 | 4.579 | 1978 | 4.691 | 1977 | 4.784 | 1976 | 4.931 | 1975 | 5.087 |
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