condition mean min max ZT0-3 8.605562 8.605562 8.605562 ZT4-7 8.240764 8.240764 8.240764 ZT8-11 8.9684665 8.9684665 8.9684665 ZT12-15 8.362391500000001 8.362391500000001 8.362391500000001 ZT16-19 8.985516 8.985516 8.985516 ZT20-23 8.6373115 8.6373115 8.6373115