condition mean min max ZT0-3 6.166076666666666 6.166076666666666 6.166076666666666 ZT4-7 6.258165 6.258165 6.258165 ZT8-11 4.38692 4.38692 4.38692 ZT12-15 5.3987549999999995 5.3987549999999995 5.3987549999999995 ZT16-19 7.71329 7.71329 7.71329 ZT20-23 7.961239999999999 7.961239999999999 7.961239999999999