Question: when did the currencies of zimbabwe first come in circulation
[{'answer': '1980', 'provenance': [{'wikipedia_id': '20596290', 'title': 'Zimbabwean dollar', 'start_paragraph_id': 1, 'start_character': 141, 'end_paragraph_id': 1, 'end_character': 145, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '20596290', 'title': 'Zimbabwean dollar', 'start_paragraph_id': 11, 'start_character': 0, 'end_paragraph_id': 11, 'end_character': 547, 'bleu_score': 0.9357524866175051, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8504945753759515129}, 'section': 'Section::::History.:Initial introduction (ZWD).\n'}]}]