condition mean min max ZT0-3 4.553635 4.553635 4.553635 ZT4-7 7.93017 7.93017 7.93017 ZT8-11 1.420675 1.420675 1.420675 ZT12-15 1.218255 1.218255 1.218255 ZT16-19 2.34004 2.34004 2.34004 ZT20-23 3.07228 3.07228 3.07228