Table:
|  | Combined Pension Plan | Post-Retirement Benefit Plans | Medicare Part D Subsidy Receipts |
| --- | --- | --- | --- |
|  |  | (Dollars in millions) |  |
| Estimated future benefit payments: |  |  |  |
| 2020 | $971 | 242 | (6) |
| 2021 | 921 | 238 | (6) |
| 2022 | 893 | 232 | (6) |
| 2023 | 868 | 226 | (5) |
| 2024 | 842 | 219 | (5) |
| 2025-2029 | 3,813 | 986 | (20) |
Paragraphs:
Expected Cash Flows
The Combined Pension Plan payments, post-retirement health care benefit payments and premiums, and life insurance premium payments are either distributed from plan assets or paid by us. The estimated benefit payments provided below are based on actuarial assumptions using the demographics of the employee and retiree populations and have been reduced by estimated participant contributions.
Question:
What assumptions are the estimated benefit payments based on?
Answer: actuarial assumptions using the demographics of the employee and retiree populations and have been reduced by estimated participant contributions