Suppose that the risk-free zero curve is flat at 1.5% per annum with continuous compounding and that defaults can occur at times 0.25 years, 0.75 years, 1.25 years, and 1.75 years in a two-year plain vanilla credit default swap with semi-annual payments. Suppose that the recovery rate is 30% and the unconditional probabilities of default (as seen at time zero) are 1% at times 0.25 years and 0.75 years, and 1.5% at times 1.25 years and 1.75 years. Estimate the credit default swap (CDS) spread in the example above.