Question: when did springfield become the capital of illinois
[{'answer': '1839', 'provenance': [{'wikipedia_id': '57706', 'title': 'Springfield, Illinois', 'start_paragraph_id': 8, 'start_character': 237, 'end_paragraph_id': 8, 'end_character': 241, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}]