condition mean min max ZT0-3 3.1663216666666667 2.98456 3.26468 ZT4-7 3.110525 3.110525 3.110525 ZT8-11 2.270505 2.270505 2.270505 ZT12-15 4.192755 3.905075 4.480435 ZT16-19 2.2962985000000002 2.2962985000000002 2.2962985000000002 ZT20-23 2.4356299999999997 2.4356299999999997 2.4356299999999997