def add_padding(bbox, padding_pct):
    """ Add the given percentage padding to the given bounding box. """

    min_lat = bbox[1]
    max_lat = bbox[3]
    min_lon = bbox[0]
    max_lon = bbox[2]

    lat_pad = ((max_lat - min_lat) / 100) * padding_pct
    lon_pad = ((max_lon - min_lon) / 100) * padding_pct

    bbox = (min_lon - lon_pad, min_lat - lat_pad,
            max_lon + lon_pad, max_lat + lat_pad)

    return bbox