WLLN for squares of U(0,3)

Let $\{X_{n}\}_{n\ge 1}$ be a sequence of independent and identically distributed random variables having $U(0,3)$ distribution. If $Y_{n}=\dfrac{1}{n}\sum_{i=1}^{n}X_{i}^{2}$, $n\ge 1$, then $\{Y_{n}\}_{n\ge 1}$ converges in probability to __________ (in integer)