condition mean min max ZT0-3 33.764257 33.764257 33.764257 ZT4-7 23.8300395 23.8300395 23.8300395 ZT8-11 25.5788675 25.5788675 25.5788675 ZT12-15 23.377285 23.377285 23.377285 ZT16-19 21.6243815 21.6243815 21.6243815 ZT20-23 28.171463 28.171463 28.171463