condition mean min max ZT0-3 2.3126145 0.5965535 3.9089349999999996 ZT4-7 1.0452265 1.0452265 1.0452265 ZT8-11 1.75041 1.75041 1.75041 ZT12-15 3.7883425 3.6080750000000004 3.96861 ZT16-19 7.932995 7.932995 7.932995 ZT20-23 8.305335 8.305335 8.305335