A zero coupon bond with an $8$ percent YTM has $20$ years to maturity. Two years later, the price of the bond remains the same due to changes in the yield to maturity.

What is the new percentage yield to maturity, using semiannual compounding?

$($Note: Round your answer to four decimal places; Use a financial calculator to solve this problem, and document the key sequences entered, like $[$N$],[$PMT$],[$CF$],$ etc.$)$