condition mean min max ZT0-3 4.580121666666667 2.1864 6.00549 ZT4-7 1.99553 1.99553 1.99553 ZT8-11 3.89329 3.89329 3.89329 ZT12-15 5.85482 5.318685 6.390955 ZT16-19 6.58503 6.58503 6.58503 ZT20-23 8.76244 8.76244 8.76244