condition mean min max ZT0-3 8.079359 8.079359 8.079359 ZT4-7 10.513255999999998 10.513255999999998 10.513255999999998 ZT8-11 11.3693805 11.3693805 11.3693805 ZT12-15 10.275959 10.275959 10.275959 ZT16-19 8.469185 8.469185 8.469185 ZT20-23 9.289062 9.289062 9.289062