condition mean min max ZT0-3 2.105786666666667 1.786335 2.297305 ZT4-7 0.91245 0.91245 0.91245 ZT8-11 1.0919720000000002 1.0919720000000002 1.0919720000000002 ZT12-15 2.469275 2.3817700000000004 2.55678 ZT16-19 2.015385 2.015385 2.015385 ZT20-23 1.6583450000000002 1.6583450000000002 1.6583450000000002