condition mean min max ZT0-3 18.065875 16.24695 19.8848 ZT4-7 17.9247 17.9247 17.9247 ZT8-11 18.05955 18.05955 18.05955 ZT12-15 0 0 0 ZT16-19 21.8729 21.8729 21.8729 ZT20-23 16.47915 16.47915 16.47915