def download_percapita(bnf):
    return stream_generated_file(downloads.extract([bnf]))
def download_ratio(bucket1, bucket2):
    b1, b2 = urllib.unquote(bucket1), urllib.unquote(bucket2)
    bucket = b1.split(',') + b2.split(',')
    return stream_generated_file(downloads.extract(bucket))