condition mean min max ZT0-3 18.513849999999998 17.2397 19.787999999999997 ZT4-7 15.20705 15.20705 15.20705 ZT8-11 11.755199999999999 11.755199999999999 11.755199999999999 ZT12-15 0 0 0 ZT16-19 16.550800000000002 16.550800000000002 16.550800000000002 ZT20-23 22.0839 22.0839 22.0839