Question: when was the federal gas tax last raised
[{'answer': '1993', 'provenance': [{'wikipedia_id': '17254227', 'title': 'Fuel taxes in the United States', 'start_paragraph_id': 1, 'start_character': 152, 'end_paragraph_id': 1, 'end_character': 156, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '17254227', 'title': 'Fuel taxes in the United States', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 472, 'bleu_score': 0.7297397647237811, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1371217622265717383}, 'section': 'Section::::Abstract.'}]}]