Question: when did they start using 925 on silver
[{'answer': '1868', 'provenance': [{'wikipedia_id': '16407659', 'title': 'Silver hallmarks', 'start_paragraph_id': 20, 'start_character': 235, 'end_paragraph_id': 20, 'end_character': 239, 'bleu_score': 1.0, 'section': 'Section::::United States.\n'}]}, {'provenance': [{'wikipedia_id': '16407659', 'title': 'Silver hallmarks', 'start_paragraph_id': 20, 'start_character': 0, 'end_paragraph_id': 20, 'end_character': 675, 'bleu_score': 0.9647542265670861, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13220851865857961438}, 'section': 'Section::::United States.\n'}]}]