Sam refuses to retire until his retirement account has a balance of at least $ 336,607 . Sam refuses to make any more deposits in the account. The account currently has a balance of $ 114,414 and earns 6% per year, compounded semi-annually. How long does Sam have before he will retire? (You are computing number of years. Round your answer to one decimal place. For example, record 14.294 years as 14.3).