condition mean min max ZT0-3 7.982294 7.982294 7.982294 ZT4-7 7.8683895 7.8683895 7.8683895 ZT8-11 7.7332985 7.7332985 7.7332985 ZT12-15 7.8629725 7.8629725 7.8629725 ZT16-19 7.868907 7.868907 7.868907 ZT20-23 7.8129925 7.8129925 7.8129925