Question: when have the cubs won the world series
[{'answer': '1907', 'provenance': [{'wikipedia_id': '6654', 'title': 'Chicago Cubs', 'start_paragraph_id': 2, 'start_character': 318, 'end_paragraph_id': 2, 'end_character': 322, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '1908', 'provenance': [{'wikipedia_id': '6654', 'title': 'Chicago Cubs', 'start_paragraph_id': 2, 'start_character': 327, 'end_paragraph_id': 2, 'end_character': 331, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '2016', 'provenance': [{'wikipedia_id': '6654', 'title': 'Chicago Cubs', 'start_paragraph_id': 2, 'start_character': 476, 'end_paragraph_id': 2, 'end_character': 480, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]