condition mean min max ZT0-3 9.787510000000001 6.48543 13.089590000000001 ZT4-7 12.9571 12.9571 12.9571 ZT8-11 6.83334 6.83334 6.83334 ZT12-15 0 0 0 ZT16-19 21.057450000000003 21.057450000000003 21.057450000000003 ZT20-23 23.17855 23.17855 23.17855