| Year | Value | | 2022 | 19,064 | | 2021 | 19,411 | | 2020 | 19,623 | | 2019 | 19,738 | | 2018 | 19,789 | | 2017 | 19,838 | | 2016 | 19,844 | | 2015 | 19,774 | | 2014 | 19,619 | | 2013 | 19,255 | | 2012 | 18,604 | | 2011 | 17,779 | | 2010 | 16,908 | | 2009 | 16,091 | | 2008 | 15,402 | | 2007 | 14,875 | | 2006 | 14,583 | | 2005 | 14,560 | | 2004 | 14,678 | | 2003 | 14,865 | | 2002 | 15,208 | | 2001 | 15,726 | | 2000 | 16,416 | | 1999 | 17,282 | | 1998 | 18,180 | | 1997 | 18,977 | | 1996 | 19,696 | | 1995 | 20,341 | | 1994 | 20,955 | | 1993 | 21,406 | | 1992 | 21,568 | | 1991 | 21,547 | | 1990 | 21,402 | | 1989 | 21,271 | | 1988 | 20,970 | | 1987 | 20,235 | | 1986 | 19,211 | | 1985 | 18,138 | | 1984 | 17,355 | | 1983 | 16,935 | | 1982 | 16,519 | | 1981 | 15,998 | | 1980 | 15,482 | | 1979 | 14,979 | | 1978 | 14,491 | | 1977 | 14,120 | | 1976 | 13,786 | | 1975 | 13,362 | | 1974 | 12,995 | | 1973 | 12,750 | | 1972 | 12,482 | | 1971 | 12,094 | | 1970 | 11,655 | | 1969 | 11,229 | | 1968 | 10,838 | | 1967 | 10,539 | | 1966 | 10,231 | | 1965 | 9,713 | | 1964 | 9,227 | | 1963 | 8,893 | | 1962 | 8,541 | | 1961 | 8,179 | | 1960 | 7,808 |
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