Let’s break this down step-by-step.

**1. Identify relevant EBITDA-like metric**  
S&P usually starts from "Operating Income Before Depreciation & Amortization" or reconstructs EBITDA using operating income plus D&A.  
From the data:

- *Operating Income Before Share of Net Income of Equity Accounted Entities* (2022): **2,206.3 million EUR**  
- *Operating Depreciation, Amortization, Provisions, and Impairment Losses* (2022): **3,178.6 million EUR**  

So:  
EBITDA ≈ 2,206.3 + 3,178.6 = **5,384.9 million EUR**

**2. Identify Net Debt**  
S&P net debt typically =  
+ Noncurrent financial liabilities (excl. concession)  
+ Current financial liabilities (excl. concession)  
+ Lease liabilities (noncurrent + current)  
- Cash & cash equivalents  
- Other liquid financial assets (sometimes)  

From 2023-01-01 (end of FY2022):  

- Noncurrent Financial Liabilities Excluding Concession: **19,692.1 million**  
- Current Financial Liabilities Excluding Concession: **6,521.4 million**  
- Noncurrent Lease Liabilities: **1,656.2 million**  
- Current Lease Liabilities: **496.5 million**  
- Less: Cash and Cash Equivalents: **(9,012.2 million)**  
- Less: Other Current Financial Assets (often includes liquid investments): **(2,213.5 million)**  

Net Debt ≈ 19,692.1 + 6,521.4 + 1,656.2 + 496.5 - 9,012.2 - 2,213.5  
= **17,140.5 million EUR**

**3. Ratio**  
Net Debt / EBITDA ≈ 17,140.5 / 5,384.9 ≈ **3.18**

<answer>3.18</answer>