condition mean min max ZT0-3 2.3008733333333335 2.1166 2.4403750000000004 ZT4-7 2.667805 2.667805 2.667805 ZT8-11 1.6729850000000002 1.6729850000000002 1.6729850000000002 ZT12-15 1.45619075 1.1094765 1.802905 ZT16-19 1.1352855 1.1352855 1.1352855 ZT20-23 1.9289199999999997 1.9289199999999997 1.9289199999999997