| Year | Value | | 2024 | 20,697 | | 2023 | 21,501 | | 2022 | 22,236 | | 2021 | 22,787 | | 2020 | 23,380 | | 2019 | 24,061 | | 2018 | 24,556 | | 2017 | 24,816 | | 2016 | 24,792 | | 2015 | 24,558 | | 2014 | 24,176 | | 2013 | 23,674 | | 2012 | 23,093 | | 2011 | 22,440 | | 2010 | 21,735 | | 2009 | 21,056 | | 2008 | 20,433 | | 2007 | 19,847 | | 2006 | 19,306 | | 2005 | 18,824 | | 2004 | 18,392 | | 2003 | 17,999 | | 2002 | 17,648 | | 2001 | 17,335 | | 2000 | 17,039 | | 1999 | 16,770 | | 1998 | 16,555 | | 1997 | 16,391 | | 1996 | 16,273 | | 1995 | 16,194 | | 1994 | 16,145 | | 1993 | 16,088 | | 1992 | 15,981 | | 1991 | 15,789 | | 1990 | 15,470 | | 1989 | 15,048 | | 1988 | 14,615 | | 1987 | 14,195 | | 1986 | 13,782 | | 1985 | 13,374 | | 1984 | 12,939 | | 1983 | 12,460 | | 1982 | 11,960 | | 1981 | 11,462 | | 1980 | 10,970 | | 1979 | 10,695 | | 1978 | 10,652 | | 1977 | 10,610 | | 1976 | 10,518 | | 1975 | 10,346 |
|