condition mean min max ZT0-3 8.314665 8.314665 8.314665 ZT4-7 7.11688 7.11688 7.11688 ZT8-11 12.25045 12.25045 12.25045 ZT12-15 11.53515 11.53515 11.53515 ZT16-19 18.5869 18.5869 18.5869 ZT20-23 7.88872 7.88872 7.88872