condition mean min max ZT0-3 2.186275 2.186275 2.186275 ZT4-7 1.43579 1.43579 1.43579 ZT8-11 2.1635 2.1635 2.1635 ZT12-15 2.1277850000000003 2.1277850000000003 2.1277850000000003 ZT16-19 2.492905 2.492905 2.492905 ZT20-23 1.761895 1.761895 1.761895