If the variance $\sigma^2$ of the data
$$\begin{array}{cccccccc} x_i & 0 & 1 & 5 & 6 & 10 & 12 & 17 \\ f_i & 3 & 2 & 3 & 2 & 6 & 3 & 3 \end{array}$$
is $k$, then the value of $\lfloor k \rfloor$ is $\underline{\hspace{1cm}}$ (where $\lfloor \cdot \rfloor$ denotes the greatest integer function).