Year | Value | 2022 | 1.882 | 2021 | 1.889 | 2020 | 1.917 | 2019 | 1.967 | 2018 | 2.054 | 2017 | 2.14 | 2016 | 2.177 | 2015 | 2.194 | 2014 | 2.2 | 2013 | 2.165 | 2012 | 2.149 | 2011 | 2.133 | 2010 | 2.137 | 2009 | 2.162 | 2008 | 2.178 | 2007 | 2.195 | 2006 | 2.227 | 2005 | 2.224 | 2004 | 2.224 | 2003 | 2.231 | 2002 | 2.323 | 2001 | 2.532 | 2000 | 2.505 | 1999 | 2.592 | 1998 | 2.67 | 1997 | 2.716 | 1996 | 2.793 | 1995 | 2.792 | 1994 | 2.852 | 1993 | 2.896 | 1992 | 2.936 | 1991 | 3.048 | 1990 | 3.126 | 1989 | 3.282 | 1988 | 3.387 | 1987 | 3.497 | 1986 | 3.629 | 1985 | 3.755 | 1984 | 3.894 | 1983 | 4.024 | 1982 | 4.175 | 1981 | 4.314 | 1980 | 4.426 | 1979 | 4.564 | 1978 | 4.672 | 1977 | 4.758 | 1976 | 4.919 | 1975 | 5.073 | 1974 | 5.23 |
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