| Year | Value | | 2022 | 31,791 | | 2021 | 31,948 | | 2020 | 32,553 | | 2019 | 33,121 | | 2018 | 33,852 | | 2017 | 34,496 | | 2016 | 34,811 | | 2015 | 35,020 | | 2014 | 35,261 | | 2013 | 35,639 | | 2012 | 36,026 | | 2011 | 36,350 | | 2010 | 36,458 | | 2009 | 36,132 | | 2008 | 35,541 | | 2007 | 34,887 | | 2006 | 34,183 | | 2005 | 33,452 | | 2004 | 32,697 | | 2003 | 31,929 | | 2002 | 31,160 | | 2001 | 30,387 | | 2000 | 29,610 | | 1999 | 29,099 | | 1998 | 29,102 | | 1997 | 29,299 | | 1996 | 29,407 | | 1995 | 29,435 | | 1994 | 29,380 | | 1993 | 29,247 | | 1992 | 29,035 | | 1991 | 28,736 | | 1990 | 28,127 | | 1989 | 26,303 | | 1988 | 23,552 | | 1987 | 20,853 | | 1986 | 18,234 | | 1985 | 15,714 | | 1984 | 13,299 | | 1983 | 10,992 | | 1982 | 8,957 | | 1981 | 7,963 | | 1980 | 7,776 | | 1979 | 7,572 | | 1978 | 7,357 | | 1977 | 7,131 | | 1976 | 6,896 | | 1975 | 6,656 | | 1974 | 6,447 | | 1973 | 6,278 | | 1972 | 6,114 | | 1971 | 5,957 | | 1970 | 5,802 | | 1969 | 5,646 | | 1968 | 5,497 | | 1967 | 5,294 | | 1966 | 5,044 | | 1965 | 4,832 | | 1964 | 4,666 | | 1963 | 4,524 | | 1962 | 4,388 | | 1961 | 4,258 | | 1960 | 4,135 |
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