Hybrid bonds are typically used to optimize funding, provide balance sheet flexibility, and manage cost of capital, especially when equity is expensive or debt capacity is constrained. From the 2022 ENI S.p.A. data, we see:
- The company has a substantial amount of long-term borrowings and liabilities, with equity around 55.7 billion and total liabilities 96.9 billion as of 2023-01-01. 
- There is no explicit listing of perpetual subordinated bonds or other clearly hybrid instruments in the provided figures, though there are references to “Perpetual Subordinated Bonds” in adjustments and costs, suggesting some hybrid features exist historically or in related instruments, but not clearly in current 2023 figures.
- The large scale of debt (Longterm Borrowings ~19.37b, Current Portion ~3.097b, short-term borrowings ~4.446b) indicates heavy leverage. The equity base is sizable, around 54.76b at 2023-01-01, implying a moderate equity cushion.
- Given the 2022 market context data (swap curves, credit indices) showing elevated yields in 2022, the cost of debt would be higher; hybrids could help optimize tax and capital structure but come with dilution and potential volatility.

Considering ENI’s size and the fact that hybrid bonds (perpetuals) are not clearly prominent in the 2023 disclosures, and given a relatively strong equity base, it would not be prudent to rely heavily on hybrids. A moderate use could be possible if strategic flexibility is needed, but without clear signals of significant hybrid instruments on the balance sheet, an answer leaning toward minimal reliance seems justified.

Therefore, I would choose 0% as the extent of reliance on hybrid bonds.

<answer>0%</answer>