condition mean min max ZT0-3 8.26902043275 7.76300798 8.7750328855 ZT4-7 7.6611289835 7.419434838666667 7.902823128333334 ZT8-11 7.7671450769999995 6.470343591666666 9.063946562333333 ZT12-15 8.381407962833332 8.298621856 8.464194069666666 ZT16-19 9.173642506333334 8.950159628666666 9.397125383999999 ZT20-23 9.1861625845 8.856770408000001 9.515554761