Question: when was the forbidden city opened to the public
[{'answer': '1912', 'provenance': [{'wikipedia_id': '69123', 'title': 'Forbidden City', 'start_paragraph_id': 1, 'start_character': 213, 'end_paragraph_id': 1, 'end_character': 217, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]