condition mean min max ZT0-3 15.7672 15.236 16.2984 ZT4-7 14.5687 14.5687 14.5687 ZT8-11 17.0955 17.0955 17.0955 ZT12-15 0 0 0 ZT16-19 19.9781 19.9781 19.9781 ZT20-23 21.5156 21.5156 21.5156