condition mean min max ZT0-3 2.6483379337499997 2.5283776835 2.768298184 ZT4-7 1.39411255525 1.0200492595000001 1.768175851 ZT8-11 1.3068355977500001 1.2682152005 1.345455995 ZT12-15 0.5472967945 0.449096917 0.645496672 ZT16-19 1.267320376 0.9166445630000001 1.6179961889999999 ZT20-23 1.9824920245000002 1.943716229 2.0212678200000003