condition mean min max ZT0-3 8.517419 8.517419 8.517419 ZT4-7 9.2064935 9.2064935 9.2064935 ZT8-11 8.7743885 8.7743885 8.7743885 ZT12-15 7.946488499999999 7.946488499999999 7.946488499999999 ZT16-19 9.001650999999999 9.001650999999999 9.001650999999999 ZT20-23 8.867188 8.867188 8.867188