condition mean min max ZT0-3 2.2864211666666665 1.0513235 2.971475 ZT4-7 0.927091 0.927091 0.927091 ZT8-11 1.1173165 1.1173165 1.1173165 ZT12-15 1.29600125 1.167134 1.4248685 ZT16-19 1.4025050000000001 1.4025050000000001 1.4025050000000001 ZT20-23 1.8425449999999999 1.8425449999999999 1.8425449999999999