| http://www.w3.org/ns/prov#value | - Educational level, which was determined by years of schooling and level at graduation, was classified into 2 groups: incomplete secondary schooling (??? 9years of education) and higher (> 9years of education including graduation from high school or higher).People who smoked tobacco products such as cigarettes, cigars or pipes over the previous month were classified as current smokers.
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