Question: who topped the forbes world's billionaires list 2017
[{'answer': 'Microsoft founder Bill Gates', 'provenance': [{'wikipedia_id': '33331732', 'title': "The World's Billionaires", 'start_paragraph_id': 2, 'start_character': 334, 'end_paragraph_id': 2, 'end_character': 362, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]