condition mean min max ZT0-3 8.605562 8.605562 8.605562 ZT4-7 9.391521999999998 9.391521999999998 9.391521999999998 ZT8-11 9.944361 9.944361 9.944361 ZT12-15 9.0282745 9.0282745 9.0282745 ZT16-19 9.091553999999999 9.091553999999999 9.091553999999999 ZT20-23 8.652048 8.652048 8.652048