To estimate the FFO / Net Debt ratio for 2022, we first determine the Funds From Operations (FFO) and the Net Debt from the provided facts.

1. **Funds From Operations (FFO)**:
The closest standard representation of FFO is the cash flow from operations before working capital requirements.
FFO = "Cash Flows From Used In Operations Before Changes In Working Capital" for the 2022 period.
FFO = 4,804,300,000 EUR.

2. **Net Debt**:
Net debt is generally calculated as the sum of short-term and long-term financial debt minus cash and cash equivalents.
- Long-term Debt = "Noncurrent Financial Liabilities Excluding Concession Liabilities" = 19,692,100,000 EUR
- Short-term Debt = "Current Financial Liabilities Excluding Concession Liabilities" = 6,521,400,000 EUR
- Cash and Cash Equivalents = "Cash And Cash Equivalents" = 9,012,200,000 EUR

Gross Financial Debt = 19,692,100,000 + 6,521,400,000 = 26,213,500,000 EUR.
Net Debt = Gross Financial Debt - Cash and Cash Equivalents 
Net Debt = 26,213,500,000 - 9,012,200,000 = 17,201,300,000 EUR.

3. **FFO / Net Debt Ratio**:
FFO / Net Debt = 4,804,300,000 / 17,201,300,000 ≈ 0.2793 (or 27.93%).

<answer>0.279</answer>