condition mean min max ZT0-3 21.75355 21.75355 21.75355 ZT4-7 18.83725 18.83725 18.83725 ZT8-11 15.5633 15.5633 15.5633 ZT12-15 17.71555 17.71555 17.71555 ZT16-19 22.902099999999997 22.902099999999997 22.902099999999997 ZT20-23 22.8563 22.8563 22.8563