Question: when was treasury single account introduced in nigeria
[{'answer': '2012', 'provenance': [{'wikipedia_id': '48292947', 'title': 'Treasury single account', 'start_paragraph_id': 1, 'start_character': 156, 'end_paragraph_id': 1, 'end_character': 160, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '48292947', 'title': 'Treasury single account', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 362, 'bleu_score': 0.8683487742803291, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9228924456930980167}, 'section': 'Section::::Abstract.'}]}]