To calculate the proportion of equity to debt, we need to first determine the total equity and total debt.

From the provided information, the total equity as of December 31, 2022, is 2,610 K€.

The total debt as of December 31, 2022, is 601 K€.

Now, we can calculate the proportion of equity to debt:

Equity: 2,610 K€
Debt: 601 K€

Equity/Debt = 2,610 / 601 ≈ 4.34

So, the proportion of equity to debt is approximately 4.34.