condition mean min max ZT0-3 7.676828333333334 4.289885 11.83895 ZT4-7 3.272125 3.272125 3.272125 ZT8-11 2.692185 2.692185 2.692185 ZT12-15 1.7595275 1.4967199999999998 2.022335 ZT16-19 1.81055 1.81055 1.81055 ZT20-23 1.319334 1.319334 1.319334