Question: who has the most clean sheets in the world
[{'answer': 'Iker Casillas', 'provenance': [{'wikipedia_id': '5348091', 'title': 'Goalkeeper (association football)', 'start_paragraph_id': 53, 'start_character': 207, 'end_paragraph_id': 53, 'end_character': 220, 'bleu_score': 1.0, 'section': 'Section::::Records.\n'}]}, {'provenance': [{'wikipedia_id': '5348091', 'title': 'Goalkeeper (association football)', 'start_paragraph_id': 56, 'start_character': 0, 'end_paragraph_id': 56, 'end_character': 407, 'bleu_score': 0.632946142071521, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5311667873354759745}, 'section': 'Section::::Records.\n'}]}]