Question: what is usa's rank on the hdi scale in 2015
[{'answer': '10', 'provenance': [{'wikipedia_id': '2694428', 'title': 'List of countries by Human Development Index', 'start_paragraph_id': 2, 'start_character': 9, 'end_paragraph_id': 2, 'end_character': 11, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]