condition mean min max ZT0-3 7.517295000000001 7.203255 7.831335 ZT4-7 9.20717 9.20717 9.20717 ZT8-11 7.5164800000000005 7.5164800000000005 7.5164800000000005 ZT12-15 0 0 0 ZT16-19 8.125485 8.125485 8.125485 ZT20-23 7.639419999999999 7.639419999999999 7.639419999999999