An investor bought a **10** year **2.5**% pa fixed coupon government bond priced at **par**. The face value is $**100**. Coupons are paid **semi-annually** and the next one is in 6 months.

**Six months later**, just **after** the coupon at that time was paid, yields suddenly and unexpectedly fell to **2**% pa. Note that all yields above are given as APR's compounding semi-annually.

What was the bond investors' historical total return over that first 6 month period, given as an effective semi-annual rate?