Year | Value | 2023 | 5.01 | 2022 | 5.037 | 2021 | 6.317 | 2020 | 6.126 | 2019 | 5.372 | 2018 | 5.442 | 2017 | 5.512 | 2016 | 5.575 | 2015 | 5.638 | 2014 | 5.703 | 2013 | 5.778 | 2012 | 5.847 | 2011 | 5.93 | 2010 | 6.049 | 2009 | 6.181 | 2008 | 6.319 | 2007 | 6.51 | 2006 | 6.634 | 2005 | 6.824 | 2004 | 7.053 | 2003 | 7.302 | 2002 | 7.598 | 2001 | 7.934 | 2000 | 8.276 | 1999 | 8.643 | 1998 | 9.037 | 1997 | 9.402 | 1996 | 9.756 | 1995 | 10.147 | 1994 | 10.517 | 1993 | 10.876 | 1992 | 11.243 | 1991 | 12.945 | 1990 | 11.962 | 1989 | 12.249 | 1988 | 12.558 | 1987 | 12.878 | 1986 | 13.218 | 1985 | 13.771 | 1984 | 13.998 | 1983 | 14.384 | 1982 | 14.805 | 1981 | 15.14 | 1980 | 15.449 | 1979 | 15.686 | 1978 | 15.935 | 1977 | 16.171 | 1976 | 16.379 | 1975 | 16.578 |
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