{"year":1960,"Nt":90}
{"year":1961,"Nt":175}
{"year":1962,"Nt":40}
{"year":1963,"Nt":45}
{"year":1964,"Nt":175}
{"year":1965,"Nt":200}
{"year":1966,"Nt":425}
{"year":1967,"Nt":425}
{"year":1968,"Nt":800}
{"year":1969,"Nt":256}
{"year":1970,"Nt":713}
{"year":1971,"Nt":198}
{"year":1972,"Nt":1819}
{"year":1973,"Nt":575}
{"year":1974,"Nt":567}
{"year":1975,"Nt":1819}
{"year":1976,"Nt":7227}
{"year":1977,"Nt":852}
{"year":1978,"Nt":216}
{"year":1979,"Nt":244}
{"year":1980,"Nt":267}
{"year":1981,"Nt":1753}
{"year":1982,"Nt":999}
{"year":1983,"Nt":1788}
{"year":1984,"Nt":143}
{"year":1985,"Nt":79}
{"year":1986,"Nt":94}