| Year | Value | | 2022 | 19,518 | | 2021 | 19,365 | | 2020 | 19,177 | | 2019 | 18,941 | | 2018 | 18,657 | | 2017 | 18,383 | | 2016 | 18,110 | | 2015 | 17,792 | | 2014 | 17,410 | | 2013 | 16,988 | | 2012 | 16,540 | | 2011 | 16,061 | | 2010 | 15,572 | | 2009 | 15,110 | | 2008 | 14,688 | | 2007 | 14,293 | | 2006 | 13,900 | | 2005 | 13,473 | | 2004 | 13,009 | | 2003 | 12,542 | | 2002 | 12,118 | | 2001 | 11,762 | | 2000 | 11,468 | | 1999 | 11,172 | | 1998 | 10,814 | | 1997 | 10,423 | | 1996 | 10,051 | | 1995 | 9,692 | | 1994 | 9,338 | | 1993 | 9,025 | | 1992 | 8,745 | | 1991 | 8,547 | | 1990 | 8,440 | | 1989 | 8,400 | | 1988 | 8,400 | | 1987 | 8,375 | | 1986 | 8,310 | | 1985 | 8,177 | | 1984 | 7,963 | | 1983 | 7,676 | | 1982 | 7,322 | | 1981 | 6,915 | | 1980 | 6,513 | | 1979 | 6,186 | | 1978 | 5,925 | | 1977 | 5,677 | | 1976 | 5,447 | | 1975 | 5,242 | | 1974 | 5,069 | | 1973 | 4,909 | | 1972 | 4,723 | | 1971 | 4,517 | | 1970 | 4,288 | | 1969 | 4,056 | | 1968 | 3,862 | | 1967 | 3,727 | | 1966 | 3,642 | | 1965 | 3,594 | | 1964 | 3,573 | | 1963 | 3,566 | | 1962 | 3,563 | | 1961 | 3,560 | | 1960 | 3,545 |
|