from typing import Dict


def get_aqi_class_pcts(aqi_cl_exps: Dict[int, float], length: float) -> dict:
    """Returns the percentages of exposures to different AQI classes as a dictionary
    (e.g. { 1: 75.0, 2: 25.0 }).

    Args:
        aqi_cl_exps: A dictionary of exposures to different AQI classes (1, 2, 3...) as
            distances (m).
        length: The length of the path.
    """

    return {
        aqi_class: round(aqi_class_length * 100 / length, 3)
        for aqi_class, aqi_class_length
        in aqi_cl_exps.items()
    }