condition mean min max ZT0-3 4.225781666666667 2.9198950000000004 5.29389 ZT4-7 0.961525 0.961525 0.961525 ZT8-11 0.8030125 0.8030125 0.8030125 ZT12-15 0.9630989999999999 0.6190155 1.3071825 ZT16-19 2.67729 2.67729 2.67729 ZT20-23 3.22343 3.22343 3.22343