Question: when did the us dollar become part of a total fiat system
[{'answer': '1971', 'provenance': [{'wikipedia_id': '22156522', 'title': 'Fiat money', 'start_paragraph_id': 2, 'start_character': 290, 'end_paragraph_id': 2, 'end_character': 294, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '22156522', 'title': 'Fiat money', 'start_paragraph_id': 38, 'start_character': 0, 'end_paragraph_id': 38, 'end_character': 400, 'bleu_score': 0.9684940092844061, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1741722851580631164}, 'section': 'Section::::History.:20th century.\n'}]}]