condition mean min max ZT0-3 8.888866666666667 3.3608000000000002 12.036750000000001 ZT4-7 3.28277 3.28277 3.28277 ZT8-11 4.379305 4.379305 4.379305 ZT12-15 9.2739075 8.476745 10.071069999999999 ZT16-19 11.0495 11.0495 11.0495 ZT20-23 15.51745 15.51745 15.51745