| Year | Value | | 2024 | 610 | | 2023 | 610 | | 2022 | 613 | | 2021 | 621 | | 2020 | 629 | | 2019 | 641 | | 2018 | 656 | | 2017 | 667 | | 2016 | 666 | | 2015 | 652 | | 2014 | 627 | | 2013 | 589 | | 2012 | 566 | | 2011 | 566 | | 2010 | 571 | | 2009 | 578 | | 2008 | 587 | | 2007 | 590 | | 2006 | 585 | | 2005 | 565 | | 2004 | 525 | | 2003 | 477 | | 2002 | 434 | | 2001 | 399 | | 2000 | 374 | | 1999 | 349 | | 1998 | 323 | | 1997 | 307 | | 1996 | 291 | | 1995 | 273 | | 1994 | 270 | | 1993 | 269 | | 1992 | 263 | | 1991 | 253 | | 1990 | 236 | | 1989 | 215 | | 1988 | 197 | | 1987 | 181 | | 1986 | 174 | | 1985 | 181 | | 1984 | 189 | | 1983 | 192 | | 1982 | 189 | | 1981 | 189 | | 1980 | 199 | | 1979 | 210 | | 1978 | 220 | | 1977 | 229 | | 1976 | 222 | | 1975 | 208 |
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