condition mean min max ZT0-3 2.749645 2.749645 2.749645 ZT4-7 2.301765 2.301765 2.301765 ZT8-11 1.8097699999999999 1.8097699999999999 1.8097699999999999 ZT12-15 2.72415 2.72415 2.72415 ZT16-19 2.94692 2.94692 2.94692 ZT20-23 4.023485 4.023485 4.023485