(9) For a positive integer $n$, let $x_{n}$ be the real root of the equation $n x^{3}+2 x-n=0$ with respect to $x$, and let $a_{n}=\left[(n+1) x_{n}\right](n=2,3, \cdots)$ (the symbol $[x]$ denotes the greatest integer not exceeding $x$). Then $\frac{1}{1005}\left(a_{2}+a_{3}+a_{4}+\cdots+a_{2011}\right)=$ $\qquad$ .