Year | Value | 2021 | 14,225 | 2019 | 13,146 | 2018 | 14,832 | 2017 | 9,482 | 2016 | 24,315 | 2015 | 24,813 | 2014 | 24,216 | 2013 | 26,796 | 2012 | 16,760 | 2011 | 18,287 | 2010 | 21,574 | 1993 | 13,700 | 1992 | 11,800 | 1991 | 12,500 | 1990 | 17,100 | 1989 | 15,100 | 1988 | 14,700 | 1987 | 11,300 | 1986 | 8,100 | 1985 | 11,800 | 1984 | 11,300 | 1983 | 12,100 | 1982 | 13,600 | 1981 | 13,200 | 1980 | 19,500 | 1979 | 17,200 | 1978 | 15,500 | 1977 | 13,900 | 1976 | 14,600 | 1975 | 15,900 | 1974 | 17,800 | 1973 | 18,000 | 1972 | 17,800 | 1971 | 20,600 | 1970 | 21,300 |
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