Year | Value | 2023 | 55.746 | 2022 | 55.948 | 2021 | 56.134 | 2020 | 56.303 | 2019 | 56.454 | 2018 | 56.589 | 2017 | 56.707 | 2016 | 56.808 | 2015 | 56.892 | 2014 | 56.959 | 2013 | 57.01 | 2012 | 57.043 | 2011 | 57.06 | 2010 | 56.941 | 2009 | 56.579 | 2008 | 56.217 | 2007 | 55.853 | 2006 | 55.489 | 2005 | 55.125 | 2004 | 54.76 | 2003 | 54.394 | 2002 | 54.028 | 2001 | 53.661 | 2000 | 53.283 | 1999 | 52.873 | 1998 | 52.464 | 1997 | 52.054 | 1996 | 51.644 | 1995 | 51.233 | 1994 | 50.823 | 1993 | 50.412 | 1992 | 50.002 | 1991 | 49.696 | 1990 | 49.681 | 1989 | 49.665 | 1988 | 49.65 | 1987 | 49.635 | 1986 | 49.62 | 1985 | 49.605 | 1984 | 49.589 | 1983 | 49.574 | 1982 | 49.559 | 1981 | 49.544 | 1980 | 49.528 | 1979 | 49.513 | 1978 | 49.498 | 1977 | 49.483 | 1976 | 49.468 | 1975 | 49.452 | 1974 | 49.437 |
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