Question: when did american chopper go off the air
[{'answer': 'December 11 , 2012', 'provenance': [{'wikipedia_id': '959765', 'title': 'American Chopper', 'start_paragraph_id': 2, 'start_character': 590, 'end_paragraph_id': 2, 'end_character': 613, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '959765', 'title': 'American Chopper', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 624, 'bleu_score': 0.8928795999605331, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3776119652355799583}, 'section': 'Section::::Abstract.'}]}]