Suppose that North bank currently charges a $3\mathrm{.}5\%$ fixed interest rate on a six $-$year auto loan and pays a $2\mathrm{.}0\%$ interest rate to customers who buy $6-$month CDs$.$ Suppose that at the end of the six$-$month period depositors roll over the funds in the CD for another six months. Then the interest rate spread is

$\%$

$.$