To determine the extent to which IBERDROLA SA should rely on hybrid bonds for its capital structure, we need to analyze the provided market data, specifically the "SUB-SEN DELTA FOR IBOXX EUR NON-FINANCIAL IG." 

The Subordinated-Senior (Sub-Sen) delta represents the yield premium or additional cost a non-financial investment-grade company must pay to issue subordinated/hybrid debt compared to standard senior corporate debt. 

Looking at the data:
- In 2020, the Sub-Sen delta averaged 1.771%.
- In 2021, the Sub-Sen delta narrowed, averaging 1.298%.
- In 2022, the Sub-Sen delta widened significantly, jumping to an average of 2.295% (and reaching up to 2.495% in a bear scenario). 

Concurrently, absolute base interest rates spiked in 2022, as shown by the 5Y, 7Y, and 10Y Swap Curves shifting from negative territory to near 2%. 

Because the spread between subordinated/hybrid debt and senior debt is exceptionally wide (and base rates are high), hybrid bonds have become a highly expensive source of capital. Purely from a cost-of-capital optimization and corporate finance perspective under these market conditions, non-financial companies should minimize or entirely avoid issuing expensive subordinated debt. Therefore, the company's capital structure should not rely on hybrid bonds.

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