| Year | Value | | 2023 | 18,150 | | 2022 | 17,780 | | 2021 | 17,456 | | 2020 | 16,950 | | 2019 | 16,268 | | 2018 | 15,606 | | 2017 | 14,988 | | 2016 | 14,350 | | 2015 | 13,709 | | 2014 | 13,094 | | 2013 | 12,521 | | 2012 | 12,008 | | 2011 | 11,572 | | 2010 | 11,212 | | 2009 | 10,907 | | 2008 | 10,638 | | 2007 | 10,399 | | 2006 | 10,177 | | 2005 | 9,965 | | 2004 | 9,787 | | 2003 | 9,661 | | 2002 | 9,563 | | 2001 | 9,463 | | 2000 | 9,342 | | 1999 | 9,198 | | 1998 | 9,003 | | 1997 | 8,771 | | 1996 | 8,567 | | 1995 | 8,412 | | 1994 | 8,286 | | 1993 | 8,207 | | 1992 | 8,175 | | 1991 | 8,124 | | 1990 | 8,031 | | 1989 | 7,911 | | 1988 | 7,776 | | 1987 | 7,624 | | 1986 | 7,468 | | 1985 | 7,309 | | 1984 | 7,138 | | 1983 | 6,953 | | 1982 | 6,759 | | 1981 | 6,574 | | 1980 | 6,412 | | 1979 | 6,278 | | 1978 | 6,175 | | 1977 | 6,094 | | 1976 | 6,001 | | 1975 | 5,877 | | 1974 | 5,728 |
|