condition mean min max ZT0-3 5.802136666666667 5.271685 6.79816 ZT4-7 6.9361250000000005 6.9361250000000005 6.9361250000000005 ZT8-11 3.30449 3.30449 3.30449 ZT12-15 3.9522325 3.82116 4.083305 ZT16-19 4.0449 4.0449 4.0449 ZT20-23 6.533345000000001 6.533345000000001 6.533345000000001