condition mean min max ZT0-3 2.527981666666667 2.35774 2.77539 ZT4-7 2.524005 2.524005 2.524005 ZT8-11 3.014775 3.014775 3.014775 ZT12-15 2.348415 1.9606999999999999 2.73613 ZT16-19 2.159775 2.159775 2.159775 ZT20-23 3.2307699999999997 3.2307699999999997 3.2307699999999997