Question: when did the usa leave the gold standard
[{'answer': '1785', 'provenance': [{'wikipedia_id': '37412', 'title': 'Gold standard', 'start_paragraph_id': 20, 'start_character': 329, 'end_paragraph_id': 20, 'end_character': 333, 'bleu_score': 1.0, 'section': 'Section::::History.:Silver.:United States.\n'}]}, {'provenance': [{'wikipedia_id': '37412', 'title': 'Gold standard', 'start_paragraph_id': 20, 'start_character': 0, 'end_paragraph_id': 20, 'end_character': 333, 'bleu_score': 0.9645876452711911, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11443162106406002554}, 'section': 'Section::::History.:Silver.:United States.\n'}]}]