condition mean min max ZT0-3 2.2570433333333333 1.556095 2.6471549999999997 ZT4-7 1.7295349999999998 1.7295349999999998 1.7295349999999998 ZT8-11 2.0620950000000002 2.0620950000000002 2.0620950000000002 ZT12-15 4.2858525 2.14026 6.431445 ZT16-19 2.214955 2.214955 2.214955 ZT20-23 2.1815550000000004 2.1815550000000004 2.1815550000000004