condition mean min max ZT0-3 7.146463333333333 6.115074999999999 8.38071 ZT4-7 3.0487599999999997 3.0487599999999997 3.0487599999999997 ZT8-11 1.9957799999999999 1.9957799999999999 1.9957799999999999 ZT12-15 1.97707425 1.0657285 2.88842 ZT16-19 1.713718 1.713718 1.713718 ZT20-23 2.248125 2.248125 2.248125