| Year | Value | | 2022 | 24,035 | | 2021 | 24,793 | | 2020 | 25,577 | | 2019 | 26,552 | | 2018 | 27,701 | | 2017 | 28,733 | | 2016 | 29,618 | | 2015 | 30,395 | | 2014 | 30,918 | | 2013 | 31,204 | | 2012 | 31,475 | | 2011 | 31,895 | | 2010 | 32,459 | | 2009 | 32,985 | | 2008 | 33,301 | | 2007 | 33,349 | | 2006 | 33,184 | | 2005 | 33,073 | | 2004 | 33,316 | | 2003 | 33,831 | | 2002 | 34,461 | | 2001 | 35,190 | | 2000 | 35,921 | | 1999 | 36,612 | | 1998 | 37,193 | | 1997 | 37,690 | | 1996 | 38,105 | | 1995 | 38,329 | | 1994 | 38,701 | | 1993 | 39,406 | | 1992 | 42,031 | | 1991 | 44,335 | | 1990 | 44,106 | | 1989 | 43,404 | | 1988 | 42,588 | | 1987 | 41,733 | | 1986 | 40,842 | | 1985 | 39,933 | | 1984 | 39,006 | | 1983 | 38,044 | | 1982 | 37,053 | | 1981 | 36,037 | | 1980 | 35,000 | | 1979 | 33,949 | | 1978 | 32,902 | | 1977 | 31,875 | | 1976 | 30,871 | | 1975 | 29,897 | | 1974 | 28,955 | | 1973 | 28,032 | | 1972 | 27,124 | | 1971 | 26,237 | | 1970 | 25,365 | | 1969 | 24,509 | | 1968 | 23,670 | | 1967 | 22,849 | | 1966 | 22,048 | | 1965 | 21,276 | | 1964 | 20,537 | | 1963 | 19,840 | | 1962 | 19,186 | | 1961 | 18,576 | | 1960 | 18,002 |
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