Listed here is the percent increase in sales for the MG Corporation over the last $5$ years.

$9\mathrm{.}4,13\mathrm{.}8,11\mathrm{.}7,11\mathrm{.}9,14\mathrm{.}7$

Determine the geometric mean percent increase in sales over the period.

Note: Round your answer to $2$ decimal places.

$\%$