title: Population structure.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003710:Demography; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D013514:Surgical Procedures, Operative / Q000191:economics