Question: when did season 12 of grey's anatomy start
[{'answer': 'September 24 , 2015', 'provenance': [{'wikipedia_id': '46641890', 'title': "Grey's Anatomy (season 12)", 'start_paragraph_id': 1, 'start_character': 129, 'end_paragraph_id': 1, 'end_character': 148, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '46641890', 'title': "Grey's Anatomy (season 12)", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 569, 'bleu_score': 0.9105581265723651, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11838236229127542170}, 'section': 'Section::::Abstract.'}]}]