condition mean min max ZT0-3 15.765386666666666 6.11101 20.7297 ZT4-7 7.70354 7.70354 7.70354 ZT8-11 6.569939999999999 6.569939999999999 6.569939999999999 ZT12-15 10.31345 9.1617 11.4652 ZT16-19 14.32235 14.32235 14.32235 ZT20-23 23.65785 23.65785 23.65785