condition mean min max ZT0-3 20.106957 20.106957 20.106957 ZT4-7 17.930596 17.930596 17.930596 ZT8-11 18.995359999999998 18.995359999999998 18.995359999999998 ZT12-15 21.2863865 21.2863865 21.2863865 ZT16-19 21.3640525 21.3640525 21.3640525 ZT20-23 30.6698525 30.6698525 30.6698525