Question: what percentage of the population have flat feet
[{'answer': '20 -- 30 %'}, {'provenance': [{'wikipedia_id': '1079375', 'title': 'Flat feet', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 319, 'bleu_score': 0.905341140211783, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4959138821778135737}, 'section': 'Section::::Abstract.'}]}]