Question: when did the currencies of the namibia first come in circulation
[{'answer': 'on 15 September 1993', 'provenance': [{'wikipedia_id': '342430', 'title': 'Namibian dollar', 'start_paragraph_id': 5, 'start_character': 47, 'end_paragraph_id': 5, 'end_character': 67, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '342430', 'title': 'Namibian dollar', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 117, 'bleu_score': 0.9021315316859231, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10696883617639389370}, 'section': 'Section::::History.\n'}]}]