Consider the real value of space vector P₂₀₂₀=[tex] \rm \left\{ \sum \limits^{n}_{i = 0}a_ix^i:a_i\in\mathbb{R} \: and \: 0 \leq n \leq2020 \right\}. [/tex]Let W be the subspace given by W=[tex] \rm \left \{ \sum \limits_{i = 0}^{n} a_ix^i \in P_{2020} :a_i =0 \: for \: all \: odd \: i\right \}[/tex] . Then the dimension of W is ____.