Question: when was to kill a mockingbird first published
[{'answer': '1960', 'provenance': [{'wikipedia_id': '73408', 'title': 'To Kill a Mockingbird', 'start_paragraph_id': 1, 'start_character': 60, 'end_paragraph_id': 1, 'end_character': 64, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '73408', 'title': 'To Kill a Mockingbird', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 437, 'bleu_score': 0.738174799239931, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17522920851139221051}, 'section': 'Section::::Abstract.'}]}]