condition mean min max ZT0-3 18.20815 18.20815 18.20815 ZT4-7 16.08685 16.08685 16.08685 ZT8-11 12.59905 12.59905 12.59905 ZT12-15 12.9346 12.9346 12.9346 ZT16-19 17.174500000000002 17.174500000000002 17.174500000000002 ZT20-23 16.91525 16.91525 16.91525