condition mean min max ZT0-3 4.349175 2.0375199999999998 6.44625 ZT4-7 1.575555 1.575555 1.575555 ZT8-11 1.9536799999999999 1.9536799999999999 1.9536799999999999 ZT12-15 3.4863425 3.25949 3.713195 ZT16-19 4.006705 4.006705 4.006705 ZT20-23 6.75015 6.75015 6.75015