To determine the optimal utilization of hybrid bonds relative to S&P Global Ratings' 15% cap on total adjusted capital, we assess the cost of capital components.

First, we establish the total adjusted capital (Total Debt + Total Equity):
1. **Total Debt** = Long-term borrowings + Current portion of long-term borrowings + Short-term borrowings
Total Debt = €68,191,000,000 + €2,835,000,000 + €18,392,000,000 = €89,418,000,000
2. **Total Equity** = €42,082,000,000
3. **Total Adjusted Capital** = €89,418,000,000 + €42,082,000,000 = €131,500,000,000

The S&P capacity for hybrid bonds to receive equity credit is 15% of the total adjusted capital:
Maximum Hybrid Capacity = 15% × €131,500,000,000 = €19,725,000,000. 

Currently, the company's perpetual hybrid bonds outstanding are €5,567,000,000, meaning there is still substantial unused capacity.

To decide the extent to which the company should utilize this capacity, we compare the cost of hybrid bonds to the cost of equity. 
Using the provided market data for 2022:
- **Base Corporate Bond Yield** (iShares Core Euro Corp Bond) = 1.085%
- **Subordinated-Senior Delta** (Iboxx EUR Non-Financial IG) = 2.295%
- **Cost of Hybrid Debt** ≈ 1.085% + 2.295% = 3.380%

Generally, the cost of equity (Ke) represents the highest risk and demands a much higher return (typically ranging from 7% to 10%+ depending on the firm's beta and the equity risk premium). Since the cost of hybrid bonds (3.380%) is far lower than the cost of equity, substituting equity with hybrid debt substantially lowers the firm's Weighted Average Cost of Capital (WACC). Furthermore, because S&P grants 50% equity credit to these hybrids up to the 15% cap, the firm can protect its credit rating metrics while obtaining significantly cheaper financing.

Because hybrids are strictly cheaper than pure equity and still offer protective equity credit to rating agency ratios, standard corporate finance WACC optimization dictates filling this bucket to its maximum allowable limit.

<answer>100%</answer>