| Year | Value | | 2024 | 18,602 | | 2023 | 18,824 | | 2022 | 19,040 | | 2021 | 19,269 | | 2020 | 19,463 | | 2019 | 19,569 | | 2018 | 19,489 | | 2017 | 19,249 | | 2016 | 18,843 | | 2015 | 18,334 | | 2014 | 17,728 | | 2013 | 16,879 | | 2012 | 15,991 | | 2011 | 15,190 | | 2010 | 13,990 | | 2009 | 12,566 | | 2008 | 11,598 | | 2007 | 10,943 | | 2006 | 10,703 | | 2005 | 11,237 | | 2004 | 12,161 | | 2003 | 13,031 | | 2002 | 13,690 | | 2001 | 14,069 | | 2000 | 14,177 | | 1999 | 14,137 | | 1998 | 13,947 | | 1997 | 13,683 | | 1996 | 13,460 | | 1995 | 13,279 | | 1994 | 13,130 | | 1993 | 13,008 | | 1992 | 12,860 | | 1991 | 12,597 | | 1990 | 12,181 | | 1989 | 11,607 | | 1988 | 10,918 | | 1987 | 10,171 | | 1986 | 9,445 | | 1985 | 8,787 | | 1984 | 8,134 | | 1983 | 7,397 | | 1982 | 6,598 | | 1981 | 5,865 | | 1980 | 5,316 | | 1979 | 5,092 | | 1978 | 5,295 | | 1977 | 5,853 | | 1976 | 6,568 | | 1975 | 7,260 |
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