Question: when did worldwide efforts to eradicate polio begin
[{'answer': '1988', 'provenance': [{'wikipedia_id': '9901652', 'title': 'Polio eradication', 'start_paragraph_id': 1, 'start_character': 119, 'end_paragraph_id': 1, 'end_character': 123, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '9901652', 'title': 'Polio eradication', 'start_paragraph_id': 46, 'start_character': 0, 'end_paragraph_id': 46, 'end_character': 492, 'bleu_score': 0.974188104609039, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 711881994973494448}, 'section': 'Section::::Timeline.:1988–2000.\n'}]}]