| Year | Value | | 2018 | 317,712 | | 2017 | 307,094 | | 2016 | 298,064 | | 2015 | 290,066 | | 2014 | 280,110 | | 2013 | 271,267 | | 2012 | 263,223 | | 2011 | 255,613 | | 2010 | 248,086 | | 2009 | 239,297 | | 2008 | 230,574 | | 2007 | 222,002 | | 2006 | 213,768 | | 2005 | 205,873 | | 2004 | 196,318 | | 2003 | 187,115 | | 2002 | 178,353 | | 2001 | 170,095 | | 2000 | 162,334 | | 1999 | 154,375 | | 1998 | 147,119 | | 1997 | 140,590 | | 1996 | 134,812 | | 1995 | 129,747 | | 1994 | 125,115 | | 1993 | 121,420 | | 1992 | 118,367 | | 1991 | 115,335 | | 1990 | 111,761 | | 1989 | 107,754 | | 1988 | 103,059 | | 1987 | 97,825 | | 1986 | 92,554 | | 1985 | 87,633 | | 1984 | 83,542 | | 1983 | 80,014 | | 1982 | 76,901 | | 1981 | 73,871 | | 1980 | 70,620 | | 1979 | 67,435 | | 1978 | 64,071 | | 1977 | 60,540 | | 1976 | 57,032 | | 1975 | 53,713 | | 1974 | 51,377 | | 1973 | 49,503 | | 1972 | 47,969 | | 1971 | 46,518 | | 1970 | 44,921 | | 1969 | 44,003 | | 1968 | 43,126 | | 1967 | 42,187 | | 1966 | 41,108 | | 1965 | 39,809 | | 1964 | 39,020 | | 1963 | 37,951 | | 1962 | 36,566 | | 1961 | 34,973 | | 1960 | 33,282 |
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