condition mean min max ZT0-3 4.751335 4.751335 4.751335 ZT4-7 4.942445 4.942445 4.942445 ZT8-11 3.2914399999999997 3.2914399999999997 3.2914399999999997 ZT12-15 2.0865650000000002 2.0865650000000002 2.0865650000000002 ZT16-19 3.460135 3.460135 3.460135 ZT20-23 3.74219 3.74219 3.74219