condition mean min max ZT0-3 18.351505 18.351505 18.351505 ZT4-7 17.221671999999998 17.221671999999998 17.221671999999998 ZT8-11 17.682544999999998 17.682544999999998 17.682544999999998 ZT12-15 17.83777 17.83777 17.83777 ZT16-19 21.6272405 21.6272405 21.6272405 ZT20-23 20.109415 20.109415 20.109415