You are given that the force of interest at time $t($in years$)$ is $\frac{1}{t+8}.$

Calculate the annual effective rate of interest in year $5.$

$6\mathrm{.}2\%$

$6\mathrm{.}6\%$

$7\mathrm{.}4\%$

$8\mathrm{.}3\%$

$9\mathrm{.}5\%$