Frank Gilbreth is the "father” of motion study. One of the first operations he studied was bricklaying. He noticed that there was unnecessary stooping, walking, and reaching. Also some bricks were damaged, which required the bricklayer to inspect each brick and find the better side before laying it. Stooping per brick laid was once for the mortar, and another for the brick. Gilbreth designed a non-stooping scaffolding platform that was raised by a lifting jack as work progressed up the wall so that the mortar and bricks were always at easy reach of the bricklayer. Motions per brick were reduced from 18 to 5, and average time went down from approximately 29 seconds per brick laid to approximately 10 seconds per brick laid. Calculate the labour productivity before and after the improvement, and the percentage of increase.