Considering the company's current capital structure, with an equity ratio of 36.3% and financial debt around 21% of assets, hybrid bonds could enhance financial flexibility and credit metrics. However, hybrid bonds are more expensive than straight debt (subordinated debt yields around 2.3% vs. senior corporate bond yields around 1.1% in 2022). Given the current low cost of straight debt and high interest coverage (18.9), the company should limit reliance on hybrid bonds to avoid excessive costs. A moderate reliance, such as 25% of the capital structure, balances flexibility and cost-effectiveness.

<answer>25%</answer>