Question: when did the us stop using leaded gas
[{'answer': 'early 2000s', 'provenance': [{'wikipedia_id': '116035', 'title': 'Tetraethyllead', 'start_paragraph_id': 22, 'start_character': 97, 'end_paragraph_id': 22, 'end_character': 108, 'bleu_score': 1.0, 'section': 'Section::::In motor fuel.:Phaseout and ban.\n'}]}, {'provenance': [{'wikipedia_id': '116035', 'title': 'Tetraethyllead', 'start_paragraph_id': 22, 'start_character': 0, 'end_paragraph_id': 22, 'end_character': 781, 'bleu_score': 0.939625262967095, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5781203926985047640}, 'section': 'Section::::In motor fuel.:Phaseout and ban.\n'}]}]