condition mean min max ZT0-3 21.369558 21.369558 21.369558 ZT4-7 23.457148 23.457148 23.457148 ZT8-11 20.8862735 20.8862735 20.8862735 ZT12-15 21.5846305 21.5846305 21.5846305 ZT16-19 25.459471999999998 25.459471999999998 25.459471999999998 ZT20-23 22.7931045 22.7931045 22.7931045