Question: when did us stop being backed by gold
[{'answer': 'October 1976', 'provenance': [{'wikipedia_id': '37412', 'title': 'Gold standard', 'start_paragraph_id': 66, 'start_character': 771, 'end_paragraph_id': 66, 'end_character': 783, 'bleu_score': 1.0, 'section': 'Section::::Abandonment of the gold standard.:Bretton Woods.\n'}]}, {'provenance': [{'wikipedia_id': '37412', 'title': 'Gold standard', 'start_paragraph_id': 66, 'start_character': 0, 'end_paragraph_id': 66, 'end_character': 974, 'bleu_score': 0.9870543337942441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6591475540866935698}, 'section': 'Section::::Abandonment of the gold standard.:Bretton Woods.\n'}]}]