condition mean min max ZT0-3 2.2275633333333333 1.8226149999999999 2.5917149999999998 ZT4-7 3.57517 3.57517 3.57517 ZT8-11 3.12373 3.12373 3.12373 ZT12-15 3.9457475 2.9940249999999997 4.89747 ZT16-19 2.453005 2.453005 2.453005 ZT20-23 2.170865 2.170865 2.170865