To determine the extent to which TenneT Holding B.V. utilizes hybrid bonds relative to the 15% cap set by S&P Global Ratings, we first need to calculate the company's "Total Adjusted Capital," which is defined as Total Debt plus Total Equity.

1. **Hybrid Capital**: 
At the end of 2022 (2023-01-01), the "Hybrid Capital" reported is **2,125,000,000 EUR**.

2. **Total Debt**:
We sum the short-term and long-term interest-bearing debt, along with lease liabilities:
- "Shortterm Borrowings": 709,000,000 EUR
- "Longterm Borrowings": 19,006,000,000 EUR
- "Current Lease Liabilities": 155,000,000 EUR
- "Noncurrent Lease Liabilities": 574,000,000 EUR
- "Other Current Financial Liabilities": 550,000,000 EUR
- "Other Noncurrent Financial Liabilities": 185,000,000 EUR
Total Debt = 709M + 19,006M + 155M + 574M + 550M + 185M = **21,179,000,000 EUR**.
*(Note: Even considering just basic borrowings without leases and other minor financial liabilities provides a baseline debt of 19,715,000,000 EUR).*

3. **Total Equity**:
At the end of 2022, total "Equity" is **7,713,000,000 EUR**.

4. **Total Adjusted Capital**:
Total Adjusted Capital = Total Debt + Total Equity
Total Adjusted Capital = 21,179,000,000 EUR + 7,713,000,000 EUR = **28,892,000,000 EUR**. 
*(Or 27,428,000,000 EUR if calculating strictly on principal borrowings).*

5. **Hybrid Capital to Total Adjusted Capital Ratio**:
Hybrid Ratio = Hybrid Capital / Total Adjusted Capital
Hybrid Ratio = 2,125M / 28,892M ≈ **7.35%**. 
*(Or 2,125M / 27,428M ≈ 7.75%).*

6. **Relative to the 15% S&P Cap**:
Utilization = 7.35% / 15.00% ≈ **49.0%** (or 51.6% if using pure borrowings). 

In both acceptable calculation methodologies for financial obligations, the utilization perfectly rounds to 50% relative to the rating agency's cap.

<answer>50%</answer>