condition mean min max ZT0-3 4.025905 4.025905 4.025905 ZT4-7 2.95851 2.95851 2.95851 ZT8-11 4.059055 4.059055 4.059055 ZT12-15 3.15021 3.15021 3.15021 ZT16-19 4.815165 4.815165 4.815165 ZT20-23 3.4644399999999997 3.4644399999999997 3.4644399999999997