condition mean min max ZT0-3 8.126986666666667 7.07381 8.80936 ZT4-7 6.22517 6.22517 6.22517 ZT8-11 6.5541149999999995 6.5541149999999995 6.5541149999999995 ZT12-15 8.941865 8.055835 9.827895 ZT16-19 6.0352 6.0352 6.0352 ZT20-23 10.252575 10.252575 10.252575