condition mean min max ZT0-3 9.404812 9.404812 9.404812 ZT4-7 8.03773 8.03773 8.03773 ZT8-11 8.906764500000001 8.906764500000001 8.906764500000001 ZT12-15 8.0374415 8.0374415 8.0374415 ZT16-19 9.209364 9.209364 9.209364 ZT20-23 8.657569500000001 8.657569500000001 8.657569500000001