condition mean min max ZT0-3 3.021955 3.021955 3.021955 ZT4-7 2.406765 2.406765 2.406765 ZT8-11 2.606255 2.606255 2.606255 ZT12-15 2.47042 2.47042 2.47042 ZT16-19 4.637385 4.637385 4.637385 ZT20-23 3.399425 3.399425 3.399425