condition mean min max ZT0-3 2.34423973025 1.8395703214999999 2.848909139 ZT4-7 2.9029477745000003 2.7120584565000003 3.0938370925000003 ZT8-11 3.808394582 3.609920502 4.006868662 ZT12-15 3.76016336375 3.4368317389999996 4.0834949885 ZT16-19 4.562773529749999 4.065952256499999 5.0595948029999995 ZT20-23 6.677796184 6.617800863499999 6.7377915045000005