condition mean min max ZT0-3 20.025775 18.54855 21.503 ZT4-7 16.97915 16.97915 16.97915 ZT8-11 17.50895 17.50895 17.50895 ZT12-15 0 0 0 ZT16-19 23.43555 23.43555 23.43555 ZT20-23 22.8812 22.8812 22.8812