condition mean min max ZT0-3 1.6816716666666667 1.19083 2.045805 ZT4-7 1.893135 1.893135 1.893135 ZT8-11 2.3374449999999998 2.3374449999999998 2.3374449999999998 ZT12-15 4.4550075 3.6977599999999997 5.212255 ZT16-19 2.777505 2.777505 2.777505 ZT20-23 2.192085 2.192085 2.192085