What is the $20-$year Maturity Risk Premium $($rmp$)?$

Years Face Coupon Market

Security Rating Maturity Value Rate Price

Treasury $1$ $ $1,0000\mathrm{.}00\%$ $ $966\mathrm{.}66$

Treasury $3$ $ $1,0002\mathrm{.}00\%$ $ $939\mathrm{.}06$

Treasury $5$ $ $1,0004\mathrm{.}40\%$ $ $932\mathrm{.}42$

Treasury $10$ $ $1,0007\mathrm{.}20\%$ $ $1,007\mathrm{.}12$

Treasury $20$ $ $1,0006\mathrm{.}60\%$ $ $908\mathrm{.}25$

Corp A A $5$ $ $1,0008\mathrm{.}10\%$ $ $1,000\mathrm{.}00$

Corp B BB $10$ $ $1,0007\mathrm{.}90\%$ $ $859\mathrm{.}88$

Corp C AA $20$ $ $1,0008\mathrm{.}20\%$ $ $972\mathrm{.}22$

What is the $20-$year Maturity Risk Premium $($rmp$)?$