How can you compute this on the BAii Plus calculator?

Parkway Void Co. issued 16-year bonds two years ago at a coupon rate of 8.5 percent. The bonds make semiannual payments. If these bonds currently sell for 109 percent of par value, what is the YTM? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Yield to maturity %