condition mean min max ZT0-3 17.140592 17.140592 17.140592 ZT4-7 18.035615999999997 18.035615999999997 18.035615999999997 ZT8-11 20.0773865 20.0773865 20.0773865 ZT12-15 16.6555575 16.6555575 16.6555575 ZT16-19 18.945718 18.945718 18.945718 ZT20-23 17.8151675 17.8151675 17.8151675