To estimate **FFO / Net debt** using an S&P-style approach:

1. **Funds from operations (FFO)** is approximated as:
   - Cash flows from operations before working-capital changes, **less cash taxes paid**, or equivalently
   - EBITDA-like operating cash generation adjusted for cash interest and taxes.

   From the data:
   - Cash flows from operations before changes in working capital = **€1,062.464m**
   - This figure appears to include tax effects presentation inconsistently, so a practical S&P-style proxy is:
     - EBITDA / Gross profit = **€1,305.021m**
     - Less net cash interest: interest paid €114.121m less interest received €29.243m = **€84.878m**
     - Less cash taxes paid = **€178.506m**

   Estimated FFO:
   \[
   1{,}305.021 - 84.878 - 178.506 = 1{,}041.637\text{ million}
   \]

2. **Net debt** is approximated from financial debt less cash and cash equivalents:
   - Noncurrent financial liabilities = **€4,722.263m**
   - Current financial liabilities = **€619.418m**
   - Gross financial debt = **€5,341.681m**
   - Cash and cash equivalents = **€559.908m**

   Net debt:
   \[
   5{,}341.681 - 559.908 = 4{,}781.773\text{ million}
   \]

3. **FFO / Net debt**:
   \[
   \frac{1{,}041.637}{4{,}781.773} = 0.2178 \approx 21.8\%
   \]

<answer>21.8%</answer>