| Year | Value | | 2022 | 23,835 | | 2021 | 23,693 | | 2020 | 23,460 | | 2019 | 23,318 | | 2018 | 23,023 | | 2017 | 22,627 | | 2016 | 22,426 | | 2015 | 22,177 | | 2014 | 21,880 | | 2013 | 21,547 | | 2012 | 21,245 | | 2011 | 21,072 | | 2010 | 20,973 | | 2009 | 20,843 | | 2008 | 20,665 | | 2007 | 20,415 | | 2006 | 20,069 | | 2005 | 19,626 | | 2004 | 19,105 | | 2003 | 18,534 | | 2002 | 17,972 | | 2001 | 17,466 | | 2000 | 17,025 | | 1999 | 16,642 | | 1998 | 16,296 | | 1997 | 15,956 | | 1996 | 15,598 | | 1995 | 15,198 | | 1994 | 14,759 | | 1993 | 14,310 | | 1992 | 13,889 | | 1991 | 13,489 | | 1990 | 13,137 | | 1989 | 12,886 | | 1988 | 12,727 | | 1987 | 12,650 | | 1986 | 12,640 | | 1985 | 12,678 | | 1984 | 12,744 | | 1983 | 12,818 | | 1982 | 12,880 | | 1981 | 12,915 | | 1980 | 12,915 | | 1979 | 12,859 | | 1978 | 12,746 | | 1977 | 12,608 | | 1976 | 12,472 | | 1975 | 12,366 | | 1974 | 12,305 | | 1973 | 12,278 | | 1972 | 12,261 | | 1971 | 12,219 | | 1970 | 12,132 | | 1969 | 11,970 | | 1968 | 11,731 | | 1967 | 11,459 | | 1966 | 11,201 | | 1965 | 11,001 | | 1964 | 10,894 | | 1963 | 10,867 | | 1962 | 10,872 | | 1961 | 10,860 | | 1960 | 10,836 |
|