condition mean min max ZT0-3 13.192985 10.20142 16.18455 ZT4-7 21.20715 21.20715 21.20715 ZT8-11 19.9152 19.9152 19.9152 ZT12-15 0 0 0 ZT16-19 15.72645 15.72645 15.72645 ZT20-23 16.78905 16.78905 16.78905