You are considering two investments: 1) buying one share Roivant Pharma for $8.00; or 2) one call option on Roivant for a premium of $2.00. The call option expires in six months and has a strike price of $12.50. (Assume that there is only one share in the call option contract.) Assume that the stock price rises to $18.50 by the option expiry date. What is the ratio of the rate of return on the call over the return on the stock? Round your answer to one decimal place.