condition mean min max ZT0-3 20.784866 20.784866 20.784866 ZT4-7 18.694302999999998 18.694302999999998 18.694302999999998 ZT8-11 19.802183499999998 19.802183499999998 19.802183499999998 ZT12-15 18.638023 18.638023 18.638023 ZT16-19 17.239821499999998 17.239821499999998 17.239821499999998 ZT20-23 17.1887125 17.1887125 17.1887125