condition mean min max ZT0-3 2.0421983333333333 1.588015 2.47516 ZT4-7 0.9423735 0.9423735 0.9423735 ZT8-11 0.8506184999999999 0.8506184999999999 0.8506184999999999 ZT12-15 1.6935925 1.460595 1.92659 ZT16-19 2.46736 2.46736 2.46736 ZT20-23 2.871225 2.871225 2.871225