condition mean min max ZT0-3 1.225631 1.225631 1.225631 ZT4-7 1.4402400000000002 1.4402400000000002 1.4402400000000002 ZT8-11 1.5364149999999999 1.5364149999999999 1.5364149999999999 ZT12-15 1.8954499999999999 1.8954499999999999 1.8954499999999999 ZT16-19 1.1560013333333334 1.1560013333333334 1.1560013333333334 ZT20-23 1.69271 1.69271 1.69271