Cardinality of $\{(x, y)\mid x \in y \}$ for Finite Stages of von Neumann Universe

Question

first time posting here, please feel free correct any formatting mistakes, thanks!
We are familiar with the definition of the von Neumann universe. Of interests here are the finite stages:
$$ V_0 = \emptyset \\ V_{n+1} = \mathcal{P}(V_n) $$ So my question is the following: for each $V_n$, what is the cardinality of the membership relation $\{(x, y) \in V_n \times V_n\mid x \in y \}$? Thank you very much!