condition mean min max ZT0-3 8.944742 8.944742 8.944742 ZT4-7 7.9421634999999995 7.9421634999999995 7.9421634999999995 ZT8-11 8.036878 8.036878 8.036878 ZT12-15 9.386175999999999 9.386175999999999 9.386175999999999 ZT16-19 9.172491 9.172491 9.172491 ZT20-23 8.151695 8.151695 8.151695