| Year | Value | | 2024 | 474 | | 2023 | 450 | | 2022 | 439 | | 2021 | 437 | | 2020 | 440 | | 2019 | 463 | | 2018 | 501 | | 2017 | 527 | | 2016 | 533 | | 2015 | 528 | | 2014 | 532 | | 2013 | 537 | | 2012 | 548 | | 2011 | 579 | | 2010 | 610 | | 2009 | 628 | | 2008 | 624 | | 2007 | 606 | | 2006 | 581 | | 2005 | 560 | | 2004 | 561 | | 2003 | 578 | | 2002 | 593 | | 2001 | 605 | | 2000 | 616 | | 1999 | 631 | | 1998 | 651 | | 1997 | 674 | | 1996 | 695 | | 1995 | 711 | | 1994 | 723 | | 1993 | 719 | | 1992 | 697 | | 1991 | 664 | | 1990 | 629 | | 1989 | 615 | | 1988 | 614 | | 1987 | 612 | | 1986 | 605 | | 1985 | 600 | | 1984 | 596 | | 1983 | 578 | | 1982 | 542 | | 1981 | 496 | | 1980 | 471 | | 1979 | 482 | | 1978 | 507 | | 1977 | 527 | | 1976 | 531 | | 1975 | 518 |
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