condition mean min max ZT0-3 7.99077 7.99077 7.99077 ZT4-7 8.253698 8.253698 8.253698 ZT8-11 8.1332715 8.1332715 8.1332715 ZT12-15 7.5391189999999995 7.5391189999999995 7.5391189999999995 ZT16-19 7.99691 7.99691 7.99691 ZT20-23 8.1937635 8.1937635 8.1937635