condition mean min max ZT0-3 8.782575 8.782575 8.782575 ZT4-7 7.798498 7.798498 7.798498 ZT8-11 8.5068315 8.5068315 8.5068315 ZT12-15 7.3220375 7.3220375 7.3220375 ZT16-19 8.165886 8.165886 8.165886 ZT20-23 7.5762564999999995 7.5762564999999995 7.5762564999999995