Question: when was the office of the prime minister created in nigeria
[{'answer': '1960', 'provenance': [{'wikipedia_id': '11043364', 'title': 'Prime Minister of Nigeria', 'start_paragraph_id': 1, 'start_character': 73, 'end_paragraph_id': 1, 'end_character': 77, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '11043364', 'title': 'Prime Minister of Nigeria', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 85, 'bleu_score': 0.8781879837907131, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10104745958297074537}, 'section': 'Section::::Abstract.'}]}]