Year | Value | 2021 | 22,680 | 2020 | 22,700 | 2019 | 22,740 | 2018 | 22,720 | 2017 | 22,700 | 2016 | 22,750 | 2015 | 22,734 | 2014 | 22,671 | 2013 | 22,585 | 2012 | 22,851 | 2011 | 22,866 | 2010 | 22,919 | 2009 | 22,965 | 2008 | 22,964 | 2007 | 22,949 | 2006 | 23,008 | 2005 | 22,738 | 2004 | 22,530 | 2003 | 22,460 | 2002 | 22,360 | 2001 | 22,220 | 2000 | 22,180 | 1999 | 22,014 | 1998 | 21,920 | 1997 | 21,500 | 1996 | 22,180 | 1995 | 22,440 | 1994 | 24,119 | 1993 | 23,837 | 1992 | 24,065 | 1991 | 24,248 | 1990 | 23,930 | 1989 | 23,858 | 1988 | 23,732 | 1987 | 24,080 | 1986 | 23,934 | 1985 | 24,084 | 1984 | 24,257 | 1983 | 24,504 | 1982 | 24,877 | 1981 | 25,167 | 1980 | 25,360 | 1979 | 25,675 | 1978 | 25,851 | 1977 | 25,976 | 1976 | 26,119 | 1975 | 26,138 | 1974 | 26,054 |
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