Suppose that based on a prepayment assumption of $200$ PSA the cash flow yield for a specific agency pass$-$through security is $7\mathrm{.}5\%$ and the stated maturity is $15$ years. Suppose further that the average life of this security is $8$ years. Assume the following yield curve for Treasuries:

Maturity

Yield

$6-$year

$6\mathrm{.}2\%$

$8-$year

$6\mathrm{.}3\%$

$10-$year

$6\mathrm{.}4\%$

$15-$year

$6\mathrm{.}6\%$

What is the nominal spread of this pass$-$through security?