Year | Value | 2022 | 20,888 | 2021 | 21,077 | 2020 | 21,050 | 2019 | 20,967 | 2018 | 21,043 | 2017 | 21,251 | 2016 | 21,575 | 2015 | 22,052 | 2014 | 22,654 | 2013 | 23,224 | 2012 | 23,563 | 2011 | 23,655 | 2010 | 23,696 | 2009 | 23,698 | 2008 | 23,592 | 2007 | 23,427 | 2006 | 23,221 | 2005 | 22,965 | 2004 | 22,661 | 2003 | 22,309 | 2002 | 21,953 | 2001 | 21,831 | 2000 | 21,841 | 1999 | 22,035 | 1998 | 22,398 | 1997 | 22,904 | 1996 | 23,422 | 1995 | 23,977 | 1994 | 24,503 | 1993 | 24,924 | 1992 | 25,273 | 1991 | 25,574 | 1990 | 25,909 | 1989 | 26,307 | 1988 | 26,728 | 1987 | 27,098 | 1986 | 27,342 | 1985 | 27,415 | 1984 | 27,290 | 1983 | 26,971 | 1982 | 26,497 | 1981 | 25,944 | 1980 | 25,443 | 1979 | 25,001 | 1978 | 24,474 | 1977 | 23,751 | 1976 | 22,712 | 1975 | 21,298 | 1974 | 19,598 | 1973 | 17,856 | 1972 | 16,375 | 1971 | 15,491 | 1970 | 15,528 | 1969 | 16,504 | 1968 | 18,101 | 1967 | 19,925 | 1966 | 21,501 | 1965 | 22,408 | 1964 | 22,505 | 1963 | 21,956 | 1962 | 21,027 | 1961 | 20,068 | 1960 | 19,446 |
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