Question: when was the last time assault weapons were banned
[{'answer': 'September 13 , 2004', 'provenance': [{'wikipedia_id': '40129756', 'title': 'Federal Assault Weapons Ban', 'start_paragraph_id': 46, 'start_character': 35, 'end_paragraph_id': 46, 'end_character': 54, 'bleu_score': 1.0, 'section': 'Section::::Efforts at renewal.\n'}]}, {'provenance': [{'wikipedia_id': '40129756', 'title': 'Federal Assault Weapons Ban', 'start_paragraph_id': 46, 'start_character': 0, 'end_paragraph_id': 46, 'end_character': 137, 'bleu_score': 0.9067110266941041, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11852959869321613471}, 'section': 'Section::::Efforts at renewal.\n'}]}]