condition mean min max ZT0-3 7.938655 7.938655 7.938655 ZT4-7 6.236335 6.236335 6.236335 ZT8-11 4.721335 4.721335 4.721335 ZT12-15 5.93815 5.93815 5.93815 ZT16-19 7.301635 7.301635 7.301635 ZT20-23 8.49264 8.49264 8.49264