Assume the zero-coupon yields on default-free securities are as summarized below:

Maturity 1-year = 3.9%, 2-year = 4.4%, 3-year = 4.7%, 4-year = 5.1%

Consider a 4-year, default free security with annual coupon payments and a face value of $1,000 that is issued at par. What is the coupon rate of this bond?