condition mean min max ZT0-3 1.7363475000000002 1.1126825 2.14026 ZT4-7 2.67569 2.67569 2.67569 ZT8-11 2.207075 2.207075 2.207075 ZT12-15 2.474315 2.410775 2.537855 ZT16-19 3.437315 3.437315 3.437315 ZT20-23 3.0687699999999998 3.0687699999999998 3.0687699999999998