condition mean min max ZT0-3 1.6540533333333334 1.2218849999999999 2.00687 ZT4-7 1.0206555 1.0206555 1.0206555 ZT8-11 1.6482799999999997 1.6482799999999997 1.6482799999999997 ZT12-15 2.2083500000000003 1.603315 2.8133850000000002 ZT16-19 2.365945 2.365945 2.365945 ZT20-23 2.60553 2.60553 2.60553