condition mean min max ZT0-3 19.040066666666664 17.681449999999998 20.5509 ZT4-7 12.815750000000001 12.815750000000001 12.815750000000001 ZT8-11 14.517949999999999 14.517949999999999 14.517949999999999 ZT12-15 23.29345 23.1959 23.391 ZT16-19 17.534950000000002 17.534950000000002 17.534950000000002 ZT20-23 22.2155 22.2155 22.2155