Question: who has won the last 10 world series
[{'answer': 'Houston Astros', 'provenance': [{'wikipedia_id': '7599168', 'title': 'List of World Series champions', 'start_paragraph_id': 4, 'start_character': 536, 'end_paragraph_id': 4, 'end_character': 550, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Chicago Cubs'}, {'answer': 'Kansas City Royals'}, {'answer': 'San Francisco Giants'}, {'answer': 'Boston Red Sox', 'provenance': [{'wikipedia_id': '7599168', 'title': 'List of World Series champions', 'start_paragraph_id': 4, 'start_character': 677, 'end_paragraph_id': 4, 'end_character': 691, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'St. Louis Cardinals', 'provenance': [{'wikipedia_id': '7599168', 'title': 'List of World Series champions', 'start_paragraph_id': 3, 'start_character': 348, 'end_paragraph_id': 3, 'end_character': 367, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'New York Yankees', 'provenance': [{'wikipedia_id': '7599168', 'title': 'List of World Series champions', 'start_paragraph_id': 3, 'start_character': 111, 'end_paragraph_id': 3, 'end_character': 127, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Philadelphia Phillies'}]