def METHOD_NAME(cls, nat_year_groups):
    filter_types = ["ACT", "SCHD", "TRFR"]
    filtered_nat_grants = {}
    for year in nat_year_groups.keys():
        year_group = []
        for amount in nat_year_groups[year]:
            if (amount["amount_type.code"] in filter_types):
                year_group.append(amount)
        filtered_nat_grants[year] = year_group
    return filtered_nat_grants