During a robotic probe exploration of the Venusian atmosphere, the atmospheric pressure at an altitude of 12 km is recorded as 42.5 bar42.5\text{ bar}42.5 bar, and the pressure at an altitude of 25 km is 15.8 bar15.8\text{ bar}15.8 bar.
Calculate the percentage decrease in atmospheric pressure from 12 km to 25 km altitude. Give your answer to 3 significant figures.