condition mean min max ZT0-3 2.359186 2.359186 2.359186 ZT4-7 1.53368 1.53368 1.53368 ZT8-11 1.197977 1.197977 1.197977 ZT12-15 1.08181 1.08181 1.08181 ZT16-19 2.4178403333333334 2.4178403333333334 2.4178403333333334 ZT20-23 1.5366099999999998 1.5366099999999998 1.5366099999999998