| Year | Value | | 2022 | 20,193 | | 2021 | 20,105 | | 2020 | 21,188 | | 2019 | 22,902 | | 2018 | 24,359 | | 2017 | 25,535 | | 2016 | 26,143 | | 2015 | 26,193 | | 2014 | 25,926 | | 2013 | 25,521 | | 2012 | 25,138 | | 2011 | 24,915 | | 2010 | 24,845 | | 2009 | 24,842 | | 2008 | 24,891 | | 2007 | 24,887 | | 2006 | 24,541 | | 2005 | 23,707 | | 2004 | 22,350 | | 2003 | 20,526 | | 2002 | 18,520 | | 2001 | 16,614 | | 2000 | 15,058 | | 1999 | 13,659 | | 1998 | 12,326 | | 1997 | 11,295 | | 1996 | 10,612 | | 1995 | 10,271 | | 1994 | 10,331 | | 1993 | 10,879 | | 1992 | 11,696 | | 1991 | 12,558 | | 1990 | 13,333 | | 1989 | 13,922 | | 1988 | 13,911 | | 1987 | 13,377 | | 1986 | 12,883 | | 1985 | 12,534 | | 1984 | 12,454 | | 1983 | 12,604 | | 1982 | 12,769 | | 1981 | 12,907 | | 1980 | 13,001 | | 1979 | 13,014 | | 1978 | 12,895 | | 1977 | 12,652 | | 1976 | 12,295 | | 1975 | 11,803 | | 1974 | 11,236 | | 1973 | 10,651 | | 1972 | 10,092 | | 1971 | 9,627 | | 1970 | 9,301 | | 1969 | 9,137 | | 1968 | 9,174 | | 1967 | 9,363 | | 1966 | 9,535 | | 1965 | 9,554 | | 1964 | 9,407 | | 1963 | 9,077 | | 1962 | 8,576 | | 1961 | 8,053 | | 1960 | 7,611 |
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