Question: what is the current population of phoenix arizona
[{'answer': '4,737,270', 'provenance': [{'wikipedia_id': '602951', 'title': 'Phoenix metropolitan area', 'start_paragraph_id': 1, 'start_character': 497, 'end_paragraph_id': 1, 'end_character': 506, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]