To estimate the Funds From Operations (FFO) to Net Debt ratio for Naturgy Energy Group SA as of the end of 2022 (using the 2022-01-01 to 2023-01-01 reporting period), we define the variables based on standard industry practices:

1.  **FFO (Funds From Operations):**
    FFO is typically calculated as Cash Flow from Operating Activities adjusted for certain non-cash items or specific variations. Given the provided data, we use the "Cash Flows From Used In Operating Activities" as the baseline.
    *   Cash Flows From Used In Operating Activities: 4,242,000,000 EUR.
    *(Note: FFO usually adds back changes in working capital, but using the provided reported operating cash flow is the standard primary proxy in this context).*

2.  **Net Debt:**
    Net Debt is calculated as Total Financial Liabilities (Current + Noncurrent Borrowings and Lease Liabilities) minus Cash and Cash Equivalents.
    *   Noncurrent Borrowings: 12,689,000,000 EUR
    *   Noncurrent Lease Liabilities: 1,309,000,000 EUR
    *   Current Borrowings (including current portion of noncurrent): 2,110,000,000 EUR
    *   Current Lease Liabilities: 177,000,000 EUR
    *   Other Current Financial Liabilities: 15,000,000 EUR
    *   Other Noncurrent Financial Liabilities: 1,000,000 EUR
    *   **Total Debt:** 12,689 + 1,309 + 2,110 + 177 + 15 + 1 = 16,301,000,000 EUR
    *   **Less: Cash and Cash Equivalents:** 3,985,000,000 EUR
    *   **Net Debt:** 16,301,000,000 - 3,985,000,000 = 12,316,000,000 EUR

3.  **FFO / Net Debt Ratio:**
    *   Ratio = 4,242,000,000 / 12,316,000,000 ≈ 0.3444

<answer>0.3444</answer>