In the given circuit below inductance values of $L_1, L_2$ and $L_3$ are same. The magnetic energy stored in the entire circuit is $\left(U_t\right)$ and that stored in the $\mathrm{L}_2$ inductor is $\left(U_l\right)$. $U_t / U_l$ is $\_\_\_\_$ .

(Ignore the mutual inductance if any)