condition mean min max ZT0-3 17.531556 17.531556 17.531556 ZT4-7 23.2782335 23.2782335 23.2782335 ZT8-11 21.884660500000003 21.884660500000003 21.884660500000003 ZT12-15 18.461374 18.461374 18.461374 ZT16-19 16.146513499999998 16.146513499999998 16.146513499999998 ZT20-23 16.476022999999998 16.476022999999998 16.476022999999998