The company's financial performance in 2022 shows significant stress, characterized by a massive net loss of 18.2 billion EUR (down from a profit of 4.8 billion EUR in 2021) and negative operating profit before depreciation and amortization (-4.9 billion EUR). The company's cash flow from operations also shifted from a healthy positive (12.6 billion EUR) in 2021 to a significant deficit (-7.4 billion EUR) in 2022.

Given this deterioration in profitability and cash flow, relying heavily on traditional debt would likely stress the company's credit rating, potentially leading to higher interest expenses in an environment where interest rates are rising (as evidenced by the provided swap curve data, where the 10Y swap rate moved from 0.053% in 2021 to 1.927% in 2022). Hybrid bonds provide a layer of equity-like support (often classified as equity under accounting or credit rating metrics) while offering the company flexibility to defer payments without triggering a default, which is critical during periods of volatility.

However, an excessive reliance on hybrids (100% or 75%) would significantly dilute existing shareholders and create perpetual payment obligations that could drain cash reserves if the firm's turnaround is delayed. A moderate allocation of 50% provides a balanced approach: it strengthens the capital structure and buffers against the volatility shown in the 2022 balance sheet, while still allowing the company to retain some leverage benefits of traditional debt. A 25% allocation is too conservative given the magnitude of the financial losses and the urgent need to shore up the balance sheet, while 50% strikes the appropriate balance for the utility sector facing structural transition risks.

<answer>50%</answer>