condition mean min max ZT0-3 2.877785 1.390295 3.818075 ZT4-7 1.27203 1.27203 1.27203 ZT8-11 1.692905 1.692905 1.692905 ZT12-15 1.48632 1.380945 1.591695 ZT16-19 3.3928599999999998 3.3928599999999998 3.3928599999999998 ZT20-23 3.6368 3.6368 3.6368