8. For a regular 2017-gon $A_{1} A_{2} \cdots A_{2017}$ inscribed in the unit circle $O$, if any two distinct vertices $A_{i}, A_{j}$ are chosen, then the probability that $\overrightarrow{O A_{i}} \cdot \overrightarrow{O A_{j}}>\frac{1}{2}$ is $\qquad$.
Fix $A_{i}$, since $\angle A_{i} O A_{j}\frac{1}{2}$ ", so $P(A)=\frac{672}{2016}=\frac{1}{3}$.