condition mean min max ZT0-3 2.236788333333333 1.7504 2.709765 ZT4-7 1.8311250000000001 1.8311250000000001 1.8311250000000001 ZT8-11 2.084145 2.084145 2.084145 ZT12-15 2.5768774999999997 2.5057799999999997 2.6479749999999997 ZT16-19 2.89223 2.89223 2.89223 ZT20-23 3.411885 3.411885 3.411885