To determine the extent to which ENI S.P.A. should utilize hybrid bonds relative to the 15% S&P Global Ratings' cap, we must analyze the company's capital structure and financial health based on the provided 2022 annual report data (as of 2023-01-01).

1.  **Total Capital Base:**
    *   Equity Attributable to Owners of Parent: 54,759,000,000 EUR
    *   Noncontrolling Interests: 471,000,000 EUR
    *   Total Equity: 55,230,000,000 EUR
    *   Short-term Borrowings: 4,446,000,000 EUR
    *   Current portion of Long-term Borrowings: 3,097,000,000 EUR
    *   Long-term Borrowings: 19,374,000,000 EUR
    *   Total Debt (approximate): 26,917,000,000 EUR
    *   Total Adjusted Capital (Debt + Equity): 26,917,000,000 + 55,230,000,000 = 82,147,000,000 EUR

2.  **S&P Hybrid Cap (15%):**
    *   15% of 82,147,000,000 EUR = 12,322,050,000 EUR.

3.  **Analysis:**
    *   ENI demonstrated strong profitability in 2022 (Profit attributable to owners of the parent: 13,887,000,000 EUR).
    *   The company has a solid equity base and has been actively managing its capital structure, including the issuance/reimbursement of hybrid instruments.
    *   Given the market conditions in 2022, characterized by a sharp rise in the swap curve (10Y moving from 0.053% in 2021 to 1.927% in 2022) and increasing cost of debt, hybrid bonds provide a strategic balance for maintaining credit ratings while optimizing the cost of capital.
    *   With an adjusted capital base exceeding 82 billion EUR, ENI possesses the financial capacity to utilize the full extent of the S&P hybrid limit to optimize its capital structure, especially considering the current macroeconomic environment and the nature of the energy sector's capital intensity. Given the financial flexibility shown, utilizing the maximum permitted capacity is a rational financial strategy.

Therefore, the company should utilize 100% of the allowed 15% cap.

<answer>100%</answer>