condition mean min max ZT0-3 7.646545 7.646545 7.646545 ZT4-7 6.739515 6.739515 6.739515 ZT8-11 3.793165 3.793165 3.793165 ZT12-15 4.31381 4.31381 4.31381 ZT16-19 6.11093 6.11093 6.11093 ZT20-23 6.44456 6.44456 6.44456