condition mean min max ZT0-3 2.38398 2.19304 2.762915 ZT4-7 2.0864149999999997 2.0864149999999997 2.0864149999999997 ZT8-11 2.2529649999999997 2.2529649999999997 2.2529649999999997 ZT12-15 4.20825 3.99531 4.42119 ZT16-19 3.623675 3.623675 3.623675 ZT20-23 3.5257050000000003 3.5257050000000003 3.5257050000000003