condition mean min max ZT0-3 21.326217 21.326217 21.326217 ZT4-7 19.865338 19.865338 19.865338 ZT8-11 23.429820999999997 23.429820999999997 23.429820999999997 ZT12-15 19.593659000000002 19.593659000000002 19.593659000000002 ZT16-19 22.994017 22.994017 22.994017 ZT20-23 27.0877765 27.0877765 27.0877765