| Year | Value | | 2022 | 38,602 | | 2021 | 36,757 | | 2020 | 35,173 | | 2019 | 33,295 | | 2018 | 31,656 | | 2017 | 30,830 | | 2016 | 30,331 | | 2015 | 30,065 | | 2014 | 30,539 | | 2013 | 31,124 | | 2012 | 31,057 | | 2011 | 30,545 | | 2010 | 29,655 | | 2009 | 28,436 | | 2008 | 26,946 | | 2007 | 25,359 | | 2006 | 23,953 | | 2005 | 22,931 | | 2004 | 22,386 | | 2003 | 22,430 | | 2002 | 22,929 | | 2001 | 23,451 | | 2000 | 23,679 | | 1999 | 23,588 | | 1998 | 23,132 | | 1997 | 22,366 | | 1996 | 21,660 | | 1995 | 21,265 | | 1994 | 21,109 | | 1993 | 21,113 | | 1992 | 21,277 | | 1991 | 21,420 | | 1990 | 21,439 | | 1989 | 21,424 | | 1988 | 21,437 | | 1987 | 21,478 | | 1986 | 21,623 | | 1985 | 21,958 | | 1984 | 22,514 | | 1983 | 23,292 | | 1982 | 24,133 | | 1981 | 24,723 | | 1980 | 24,867 | | 1979 | 24,518 | | 1978 | 23,629 | | 1977 | 22,400 | | 1976 | 21,333 | | 1975 | 20,737 | | 1974 | 20,595 | | 1973 | 20,920 | | 1972 | 21,543 | | 1971 | 21,974 | | 1970 | 21,913 | | 1969 | 21,382 | | 1968 | 20,372 | | 1967 | 18,974 | | 1966 | 17,549 | | 1965 | 16,387 | | 1964 | 15,479 | | 1963 | 14,793 | | 1962 | 14,309 | | 1961 | 13,813 | | 1960 | 13,151 |
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