condition mean min max ZT0-3 2.406035 2.406035 2.406035 ZT4-7 1.5857999999999999 1.5857999999999999 1.5857999999999999 ZT8-11 1.662955 1.662955 1.662955 ZT12-15 2.620025 2.620025 2.620025 ZT16-19 3.6899249999999997 3.6899249999999997 3.6899249999999997 ZT20-23 3.40616 3.40616 3.40616