condition mean min max ZT0-3 20.41776666666667 19.67885 20.8516 ZT4-7 14.933699999999998 14.933699999999998 14.933699999999998 ZT8-11 17.031750000000002 17.031750000000002 17.031750000000002 ZT12-15 15.786200000000001 15.00365 16.56875 ZT16-19 16.038249999999998 16.038249999999998 16.038249999999998 ZT20-23 21.89895 21.89895 21.89895