import csv


def load_penetration(scenario, path):
    """
    Load penetration forecast.

    """
    output = {}
    with open(path, 'r') as source:
        reader = csv.DictReader(source)
        for row in reader:
            if row['scenario'] == scenario.split('_')[0]:
                output[int(row['year'])] = float(row['penetration'])

    return output