For a natural number $n$, let $a _ { n }$ be the $n$-th smallest $x$-coordinate among the intersection points of the line $y = n$ and the graph of the function $y = \tan x$ in the first quadrant.
What is the value of $\lim _ { n \rightarrow \infty } \frac { a _ { n } } { n }$? [4 points]\\
(1) $\frac { \pi } { 4 }$\\
(2) $\frac { \pi } { 2 }$\\
(3) $\frac { 3 } { 4 } \pi$\\
(4) $\pi$\\
(5) $\frac { 5 } { 4 } \pi$