condition mean min max ZT0-3 3.32705 3.32705 3.32705 ZT4-7 1.6991999999999998 1.6991999999999998 1.6991999999999998 ZT8-11 2.601465 2.601465 2.601465 ZT12-15 3.0351 3.0351 3.0351 ZT16-19 4.388185 4.388185 4.388185 ZT20-23 4.785455 4.785455 4.785455