Question: when was delhi became the capital of india
[{'answer': '1931', 'provenance': [{'wikipedia_id': '37756', 'title': 'Delhi', 'start_paragraph_id': 25, 'start_character': 472, 'end_paragraph_id': 25, 'end_character': 476, 'bleu_score': 1.0, 'section': 'Section::::History.:Colonial Period.\n'}]}, {'provenance': [{'wikipedia_id': '37756', 'title': 'Delhi', 'start_paragraph_id': 25, 'start_character': 0, 'end_paragraph_id': 25, 'end_character': 637, 'bleu_score': 0.659805647116355, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 525723833712155355}, 'section': 'Section::::History.:Colonial Period.\n'}]}]