| Year | Value | | 2022 | 17,864 | | 2021 | 18,526 | | 2020 | 19,104 | | 2019 | 19,087 | | 2018 | 18,634 | | 2017 | 18,189 | | 2016 | 17,666 | | 2015 | 17,034 | | 2014 | 16,341 | | 2013 | 15,613 | | 2012 | 14,958 | | 2011 | 14,406 | | 2010 | 13,878 | | 2009 | 13,361 | | 2008 | 12,856 | | 2007 | 12,383 | | 2006 | 11,906 | | 2005 | 11,415 | | 2004 | 10,963 | | 2003 | 10,575 | | 2002 | 10,294 | | 2001 | 10,201 | | 2000 | 10,067 | | 1999 | 10,044 | | 1998 | 10,148 | | 1997 | 10,406 | | 1996 | 10,841 | | 1995 | 11,277 | | 1994 | 11,668 | | 1993 | 11,854 | | 1992 | 11,753 | | 1991 | 11,335 | | 1990 | 10,658 | | 1989 | 9,836 | | 1988 | 8,948 | | 1987 | 8,147 | | 1986 | 7,494 | | 1985 | 7,006 | | 1984 | 6,684 | | 1983 | 6,509 | | 1982 | 6,423 | | 1981 | 6,375 | | 1980 | 6,375 | | 1979 | 6,375 | | 1978 | 6,337 | | 1977 | 6,293 | | 1976 | 6,206 | | 1975 | 6,103 | | 1974 | 6,068 | | 1973 | 6,097 | | 1972 | 6,178 | | 1971 | 6,302 | | 1970 | 6,440 | | 1969 | 6,546 | | 1968 | 6,547 | | 1967 | 6,388 | | 1966 | 6,084 | | 1965 | 5,793 | | 1964 | 5,581 | | 1963 | 5,393 | | 1962 | 5,213 | | 1961 | 5,003 | | 1960 | 4,794 |
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