| Year | Value | | 2023 | 740 | | 2022 | 740 | | 2021 | 740 | | 2020 | 740 | | 2019 | 740 | | 2018 | 740 | | 2017 | 720 | | 2016 | 710 | | 2015 | 710 | | 2014 | 710 | | 2013 | 702 | | 2012 | 695 | | 2011 | 688 | | 2010 | 681 | | 2009 | 674 | | 2008 | 667 | | 2007 | 660 | | 2006 | 653 | | 2005 | 646 | | 2004 | 652 | | 2003 | 662 | | 2002 | 657 | | 2001 | 663 | | 2000 | 660 | | 1999 | 660 | | 1998 | 660 | | 1997 | 660 | | 1996 | 660 | | 1995 | 650 | | 1994 | 650 | | 1993 | 650 | | 1992 | 640 | | 1991 | 610 | | 1990 | 610 | | 1989 | 600 | | 1988 | 610 | | 1987 | 610 | | 1986 | 600 | | 1985 | 590 | | 1984 | 590 | | 1983 | 580 | | 1982 | 570 | | 1981 | 560 | | 1980 | 550 | | 1979 | 530 | | 1978 | 520 | | 1977 | 520 | | 1976 | 520 |
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