condition mean min max ZT0-3 8.991865 8.991865 8.991865 ZT4-7 8.942519 8.942519 8.942519 ZT8-11 8.6560235 8.6560235 8.6560235 ZT12-15 8.339408500000001 8.339408500000001 8.339408500000001 ZT16-19 8.386630499999999 8.386630499999999 8.386630499999999 ZT20-23 10.814544000000001 10.814544000000001 10.814544000000001