To assess the appropriate level of hybrid bond issuance for Iberdrola S.A., we analyze the provided financial data for the fiscal year ended December 31, 2022:

1.  **Capital Structure and Leverage:**
    *   **Equity:** The total Equity as of 2023-01-01 is 58.114 billion EUR.
    *   **Financial Liabilities:** The sum of "Noncurrent Financial Liabilities" (44.216 billion EUR) and "Current Financial Liabilities" (25.079 billion EUR) is 69.295 billion EUR.
    *   **Hybrid Debt:** The entity already has "Instrumentos De Capital Con Caracteristicas De Pasivo Financiero No Corriente" (576 million EUR) and "Corriente" (87 million EUR), totaling ~663 million EUR.
    *   **Total Adjusted Capital:** Based on the S&P definition (Equity + Adjusted Debt), the total is approximately 127.4 billion EUR. 15% of this total is approximately 19.1 billion EUR.

2.  **Financial and Investment Context:**
    *   **Capex Intensity:** "Purchase of Property Plant And Equipment" was 6.277 billion EUR in 2022, and "Construction In Progress" increased from 9.062 billion EUR to 11.513 billion EUR. This demonstrates a significant, sustained capital investment program required for growth in the utility sector.
    *   **Financial Performance:** The company shows strong EBITDA (13.228 billion EUR in 2022 vs 12.006 billion EUR in 2021) and healthy profit growth. However, interest costs are rising: "Finance Costs" rose from 2.268 billion EUR to 3.042 billion EUR, reflecting a tightening interest rate environment (Swap curves 2020-2022 show a shift from negative rates to ~2%).
    *   **Refinancing/Funding Needs:** Iberdrola has high ongoing capex requirements for renewable energy transition and grid infrastructure. While the company is profitable, the scale of investment requires significant capital to maintain its rating and leverage trajectory amidst rising rates.

3.  **Rationale for Hybrid Bonds:**
    *   Hybrid bonds provide rating agencies with equity-like credit treatment, which is valuable for an entity with heavy, long-term infrastructure investment needs. 
    *   Given the "A" range rating typical for major European utilities and the need to preserve this rating while funding large-scale, essential infrastructure, a moderate-to-high reliance on hybrid support is prudent. 
    *   However, because Iberdrola is already profitable and has substantial equity, it is not in immediate distress. The issuance of 3 billion EUR per year (the maximum allowed under the prompt) aligns with a strategy of "meaningful improvement" to leverage metrics rather than a "transformational" requirement for survival. 
    *   A level of 7.5% balances the need for leverage optimization (to counteract rising finance costs) with the strength of the current balance sheet.

<answer>7.5%</answer>