condition mean min max ZT0-3 2.0164869999999997 1.049221 2.554245 ZT4-7 0.89687 0.89687 0.89687 ZT8-11 3.33375 3.33375 3.33375 ZT12-15 5.46045 4.91122 6.0096799999999995 ZT16-19 6.79497 6.79497 6.79497 ZT20-23 3.095045 3.095045 3.095045