Fibonacci Ratio I

Let $F_n$ be the $n$th Fibonacci number, where $F_0 = 0, F_1 = 1,$ and $F_{n} = F_{n-1} + F_{n-2}$ for $n \geq 2$. If it exists, find $\displaystyle \lim_{n \rightarrow \infty} \dfrac{F_{n+1}}{F_n}$ to the nearest thousandth. Otherwise, report $-1$.