condition mean min max ZT0-3 8.975782 8.975782 8.975782 ZT4-7 8.010473 8.010473 8.010473 ZT8-11 8.7645765 8.7645765 8.7645765 ZT12-15 8.8507935 8.8507935 8.8507935 ZT16-19 8.554698 8.554698 8.554698 ZT20-23 9.0013745 9.0013745 9.0013745