Question: what is the population of phoenix metro area
[{'answer': '4,574,351'}, {'provenance': [{'wikipedia_id': '602951', 'title': 'Phoenix metropolitan area', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 731, 'bleu_score': 0.829569024385143, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3616961021380679259}, 'section': 'Section::::Abstract.'}]}]