condition mean min max ZT0-3 8.941959 8.941959 8.941959 ZT4-7 9.475399 9.475399 9.475399 ZT8-11 10.1795535 10.1795535 10.1795535 ZT12-15 9.788507 9.788507 9.788507 ZT16-19 8.4435775 8.4435775 8.4435775 ZT20-23 9.069776999999998 9.069776999999998 9.069776999999998