A four-year corporate bond provides a coupon of 6% per year payable semi-annually and has a yield of 5% expressed with continuous compounding. The risk-free yield curve is flat at 2% with continuous compounding. Assume that defaults can take place at the end of each year (immediately before a coupon or principal payment) and the recovery rate is 20%. Estimate the risk-neutral default probability, Q, on the assumption that it is the same each year.