The diagram shows a rectangle, PQRSPQRSPQRS, and a semi-circle. QR QR\,QR is the diameter of the semi-circle. PQ=20 cmPQ = 20\text{ cm}PQ=20 cm and QR=14 cmQR = 14\text{ cm}QR=14 cm.

Calculate the percentage of the area of the rectangle that is shaded. Give your answer correct to 1 decimal place.