condition mean min max ZT0-3 7.529405411000001 6.797895819666667 8.260915002333334 ZT4-7 6.771630638666666 6.507746862333334 7.035514415 ZT8-11 6.974468220833334 6.766334181333334 7.182602260333333 ZT12-15 6.399885576333333 6.061914750666666 6.737856402 ZT16-19 6.2773877559999995 6.204626045 6.350149467 ZT20-23 7.671835700000001 6.554069543000001 8.789601857000001