condition mean min max ZT0-3 8.777757 8.777757 8.777757 ZT4-7 8.737451 8.737451 8.737451 ZT8-11 9.473327000000001 9.473327000000001 9.473327000000001 ZT12-15 9.4749445 9.4749445 9.4749445 ZT16-19 9.845987000000001 9.845987000000001 9.845987000000001 ZT20-23 9.108325 9.108325 9.108325