condition mean min max ZT0-3 3.5014950000000002 3.5014950000000002 3.5014950000000002 ZT4-7 1.567195 1.567195 1.567195 ZT8-11 1.9865499999999998 1.9865499999999998 1.9865499999999998 ZT12-15 3.2959300000000002 3.2959300000000002 3.2959300000000002 ZT16-19 5.931675 5.931675 5.931675 ZT20-23 4.547005 4.547005 4.547005