Question: when did dustin johnson win the us open
[{'answer': '2016', 'provenance': [{'wikipedia_id': '19630743', 'title': 'Dustin Johnson', 'start_paragraph_id': 2, 'start_character': 16, 'end_paragraph_id': 2, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]