Question: when was mr freeze built at six flags
[{'answer': '1998', 'provenance': [{'wikipedia_id': '32156860', 'title': 'Mr. Freeze (roller coaster)', 'start_paragraph_id': 3, 'start_character': 23, 'end_paragraph_id': 3, 'end_character': 27, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '32156860', 'title': 'Mr. Freeze (roller coaster)', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 528, 'bleu_score': 0.9776501033621461, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8746917009752870113}, 'section': 'Section::::History.:Mr. Freeze (1998–2011).\n'}]}]