condition mean min max ZT0-3 2.244535 2.244535 2.244535 ZT4-7 2.053995 2.053995 2.053995 ZT8-11 1.8547449999999999 1.8547449999999999 1.8547449999999999 ZT12-15 1.929695 1.929695 1.929695 ZT16-19 2.167055 2.167055 2.167055 ZT20-23 2.0920050000000003 2.0920050000000003 2.0920050000000003