Determine the nominal annual rate of interest of the following ordinary general annuity.

$\backslash$table$[[$Future Value,$\backslash$table$[[$Periodic$],[$Payment$]],\backslash$table$[[$Payment$],[$Interval$]],$Term,$\backslash$table$[[$Conversion$],[$Period$]]],[$$$28,000,$$$220,1$ month,$8$ years,semi$-$annually$]]$

The nominal annual rate of interest is $\%$ compounded semi$-$annually.

$($Round to two decimal places as needed.$)$