condition mean min max ZT0-3 3.478591666666667 2.14895 4.2621 ZT4-7 1.6761499999999998 1.6761499999999998 1.6761499999999998 ZT8-11 1.77412 1.77412 1.77412 ZT12-15 2.239635 2.191045 2.288225 ZT16-19 3.2655 3.2655 3.2655 ZT20-23 4.65972 4.65972 4.65972