condition mean min max ZT0-3 3.931635 3.931635 3.931635 ZT4-7 3.176535 3.176535 3.176535 ZT8-11 2.301765 2.301765 2.301765 ZT12-15 2.237155 2.237155 2.237155 ZT16-19 2.652075 2.652075 2.652075 ZT20-23 3.560965 3.560965 3.560965