condition mean min max ZT0-3 8.867276 8.867276 8.867276 ZT4-7 7.969822000000001 7.969822000000001 7.969822000000001 ZT8-11 8.011232 8.011232 8.011232 ZT12-15 7.674026 7.674026 7.674026 ZT16-19 7.6625385 7.6625385 7.6625385 ZT20-23 7.847117 7.847117 7.847117