$($Expected return and risk$)$ The following data represent returns for the common stocks over a one$-$year period.

Probability Returns

Google ATT

$0\mathrm{.}1-20\%-10\%$

$0\mathrm{.}28\mathrm{.}5\%4\%$

$0\mathrm{.}28\mathrm{.}5\%13\mathrm{.}4\%$

$0\mathrm{.}3-18\%20\%$

$0\mathrm{.}24\mathrm{.}6\%-6\%$

The mean $($expected$)$ return of Google is $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\%.($Keep the sign and two decimal numbers.$)$