Problem $7-15$ Yield to Call $($LG$7-6)$

A $6\mathrm{.}90$ percent coupon bond with $28$ years left to maturity can be called in nine years. The call premium is one year of coupon payments. It is offered for sale at $$1,106\mathrm{.}85.$ What is the yield to call of the bond? $($Assume interest payments are semiannual.$)$ Note: Round your answer to $2$ decimal places.

Yield to call $\%$