A person borrowed $10000 for four years at a variable interest rate. They will make an interest payment to the lender at the end of each year and also repay $10000 at the end of 4 years. The one-year spot rate is 4.0% the two-year spot rate is 4.5%, the three-year spot rate is 6.0%, and the four-year spot rate is 7.0% They decide to enter into an interest rate swap to fix the interest rate for 4 years. Determine the level swap rate R.