Question: when did the first episode of rugrats air
[{'answer': 'August 11 , 1991', 'provenance': [{'wikipedia_id': '186301', 'title': 'Rugrats', 'start_paragraph_id': 1, 'start_character': 24, 'end_paragraph_id': 1, 'end_character': 40, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]