condition mean min max ZT0-3 6.865135 6.865135 6.865135 ZT4-7 5.913295 5.913295 5.913295 ZT8-11 4.91976 4.91976 4.91976 ZT12-15 5.433835 5.433835 5.433835 ZT16-19 7.085315 7.085315 7.085315 ZT20-23 7.48606 7.48606 7.48606